diff --git a/CHANGELOG.md b/CHANGELOG.md
index cc627eee63da..a35f09f8192f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -84,6 +84,8 @@
 - `[@jest/source-map]`: Extract `getCallsite` function from `jest-util` into a new separate package ([#8029](https://github.com/facebook/jest/pull/8029))
 - `[@jest/console]`: Extract custom `console` implementations from `jest-util` into a new separate package ([#8030](https://github.com/facebook/jest/pull/8030))
 - `[docs]`: Improve runAllTimers doc (it exhausts the micro-task queue) ([#8031](https://github.com/facebook/jest/pull/8031))
+- `[jest-cli]`: Migrate to TypeScript ([#8024](https://github.com/facebook/jest/pull/8024))
+- `[jest]`: Migrate to TypeScript ([#8024](https://github.com/facebook/jest/pull/8024))
 
 ### Performance
 
diff --git a/e2e/__tests__/__snapshots__/showConfig.test.ts.snap b/e2e/__tests__/__snapshots__/showConfig.test.ts.snap
index 2778cca75a7f..93748d2d53f6 100644
--- a/e2e/__tests__/__snapshots__/showConfig.test.ts.snap
+++ b/e2e/__tests__/__snapshots__/showConfig.test.ts.snap
@@ -100,6 +100,7 @@ exports[`--showConfig outputs config info and exits 1`] = `
     "filter": null,
     "globalSetup": null,
     "globalTeardown": null,
+    "json": false,
     "listTests": false,
     "maxConcurrency": 5,
     "maxWorkers": "[maxWorkers]",
diff --git a/e2e/__tests__/runProgramatically.test.ts b/e2e/__tests__/runProgrammatically.test.ts
similarity index 87%
rename from e2e/__tests__/runProgramatically.test.ts
rename to e2e/__tests__/runProgrammatically.test.ts
index 5e57c8598414..d6eecf7eac09 100644
--- a/e2e/__tests__/runProgramatically.test.ts
+++ b/e2e/__tests__/runProgrammatically.test.ts
@@ -9,7 +9,7 @@ import {resolve} from 'path';
 
 import {run} from '../Utils';
 
-const dir = resolve(__dirname, '..', 'run-programatically');
+const dir = resolve(__dirname, '..', 'run-programmatically');
 
 test('run Jest programatically', () => {
   const {stdout} = run(`node index.js --version`, dir);
diff --git a/e2e/run-programatically/index.js b/e2e/run-programmatically/index.js
similarity index 100%
rename from e2e/run-programatically/index.js
rename to e2e/run-programmatically/index.js
diff --git a/e2e/run-programmatically/package.json b/e2e/run-programmatically/package.json
new file mode 100644
index 000000000000..e886f90ea628
--- /dev/null
+++ b/e2e/run-programmatically/package.json
@@ -0,0 +1,6 @@
+{
+  "name": "run-programmatically",
+  "version": "1.0.0",
+  "dependencies": {},
+  "jest": {}
+}
diff --git a/packages/jest-cli/package.json b/packages/jest-cli/package.json
index 3b37a7743958..f86edacc6a29 100644
--- a/packages/jest-cli/package.json
+++ b/packages/jest-cli/package.json
@@ -3,8 +3,10 @@
   "description": "Delightful JavaScript Testing.",
   "version": "24.1.0",
   "main": "build/index.js",
+  "types": "build/index.d.ts",
   "dependencies": {
     "@jest/core": "^24.1.0",
+    "@jest/types": "^24.1.0",
     "chalk": "^2.0.1",
     "exit": "^0.1.2",
     "import-local": "^2.0.0",
diff --git a/packages/jest-cli/src/__tests__/cli/args.test.js b/packages/jest-cli/src/__tests__/cli/args.test.ts
similarity index 79%
rename from packages/jest-cli/src/__tests__/cli/args.test.js
rename to packages/jest-cli/src/__tests__/cli/args.test.ts
index 91945fb17e55..8b1c3a291637 100644
--- a/packages/jest-cli/src/__tests__/cli/args.test.js
+++ b/packages/jest-cli/src/__tests__/cli/args.test.ts
@@ -6,55 +6,56 @@
  *
  */
 
-'use strict';
-
-import type {Argv} from 'types/Argv';
+import {Config} from '@jest/types';
 import {check} from '../../cli/args';
 import {buildArgv} from '../../cli';
 
 describe('check', () => {
   it('returns true if the arguments are valid', () => {
-    const argv: Argv = {};
+    const argv = {} as Config.Argv;
     expect(check(argv)).toBe(true);
   });
 
   it('raises an exception if runInBand and maxWorkers are both specified', () => {
-    const argv: Argv = {maxWorkers: 2, runInBand: true};
+    const argv = {maxWorkers: 2, runInBand: true} as Config.Argv;
     expect(() => check(argv)).toThrow(
       'Both --runInBand and --maxWorkers were specified',
     );
   });
 
   it('raises an exception if onlyChanged and watchAll are both specified', () => {
-    const argv: Argv = {onlyChanged: true, watchAll: true};
+    const argv = {onlyChanged: true, watchAll: true} as Config.Argv;
     expect(() => check(argv)).toThrow(
       'Both --onlyChanged and --watchAll were specified',
     );
   });
 
   it('raises an exception when lastCommit and watchAll are both specified', () => {
-    const argv: Argv = {lastCommit: true, watchAll: true};
+    const argv = {lastCommit: true, watchAll: true} as Config.Argv;
     expect(() => check(argv)).toThrow(
       'Both --lastCommit and --watchAll were specified',
     );
   });
 
   it('raises an exception if findRelatedTests is specified with no file paths', () => {
-    const argv: Argv = {_: [], findRelatedTests: true};
+    const argv = {
+      _: [] as Array<string>,
+      findRelatedTests: true,
+    } as Config.Argv;
     expect(() => check(argv)).toThrow(
       'The --findRelatedTests option requires file paths to be specified',
     );
   });
 
   it('raises an exception if maxWorkers is specified with no number', () => {
-    const argv: Argv = {maxWorkers: undefined};
+    const argv = ({maxWorkers: undefined} as unknown) as Config.Argv;
     expect(() => check(argv)).toThrow(
       'The --maxWorkers (-w) option requires a number to be specified',
     );
   });
 
   it('raises an exception if config is not a valid JSON string', () => {
-    const argv: Argv = {config: 'x:1'};
+    const argv = {config: 'x:1'} as Config.Argv;
     expect(() => check(argv)).toThrow(
       'The --config option requires a JSON string literal, or a file path with a .js or .json extension',
     );
@@ -63,9 +64,11 @@ describe('check', () => {
 
 describe('buildArgv', () => {
   it('should return only camelcased args ', () => {
+    // @ts-ignore
     const mockProcessArgv = jest
       .spyOn(process.argv, 'slice')
       .mockImplementation(() => ['--clear-mocks']);
+    // @ts-ignore
     const actual = buildArgv(null);
     expect(actual).not.toHaveProperty('clear-mocks');
     expect(actual).toHaveProperty('clearMocks', true);
diff --git a/packages/jest-cli/src/cli/args.js b/packages/jest-cli/src/cli/args.ts
similarity index 83%
rename from packages/jest-cli/src/cli/args.js
rename to packages/jest-cli/src/cli/args.ts
index 184c09afd593..b98baa1791b1 100644
--- a/packages/jest-cli/src/cli/args.js
+++ b/packages/jest-cli/src/cli/args.ts
@@ -3,16 +3,13 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {Argv} from 'types/Argv';
-
+import {Config} from '@jest/types';
 import {isJSONString} from 'jest-config';
 import isCI from 'is-ci';
 
-export const check = (argv: Argv) => {
+export const check = (argv: Config.Argv) => {
   if (argv.runInBand && argv.hasOwnProperty('maxWorkers')) {
     throw new Error(
       'Both --runInBand and --maxWorkers were specified, but these two ' +
@@ -80,7 +77,7 @@ export const options = {
   automock: {
     default: undefined,
     description: 'Automock all files by default.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   bail: {
     alias: 'b',
@@ -94,27 +91,27 @@ export const options = {
       'Respect the "browser" field in package.json ' +
       'when resolving modules. Some packages export different versions ' +
       'based on whether they are operating in node.js or a browser.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   cache: {
     default: undefined,
     description:
       'Whether to use the transform cache. Disable the cache ' +
       'using --no-cache.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   cacheDirectory: {
     description:
       'The directory where Jest should store its cached ' +
       ' dependency information.',
-    type: 'string',
+    type: 'string' as 'string',
   },
   changedFilesWithAncestor: {
     default: undefined,
     description:
       'Runs tests related to the current changes and the changes made in the ' +
       'last commit. Behaves similarly to `--onlyChanged`.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   changedSince: {
     description:
@@ -122,7 +119,7 @@ export const options = {
       'current branch has diverged from the given branch, then only changes ' +
       'made locally will be tested. Behaves similarly to `--onlyChanged`.',
     nargs: 1,
-    type: 'string',
+    type: 'string' as 'string',
   },
   ci: {
     default: isCI,
@@ -130,48 +127,49 @@ export const options = {
       'Whether to run Jest in continuous integration (CI) mode. ' +
       'This option is on by default in most popular CI environments. It will ' +
       ' prevent snapshots from being written unless explicitly requested.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   clearCache: {
     default: undefined,
     description:
       'Clears the configured Jest cache directory and then exits. ' +
       'Default directory can be found by calling jest --showConfig',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   clearMocks: {
     default: undefined,
     description:
       'Automatically clear mock calls and instances between every ' +
       'test. Equivalent to calling jest.clearAllMocks() between each test.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   collectCoverage: {
     default: undefined,
     description: 'Alias for --coverage.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   collectCoverageFrom: {
     description:
       'A glob pattern relative to <rootDir> matching the files that coverage ' +
       'info needs to be collected from.',
-    type: 'string',
+    type: 'string' as 'string',
   },
   collectCoverageOnlyFrom: {
     description: 'Explicit list of paths coverage will be restricted to.',
-    type: 'array',
+    string: true as true,
+    type: 'array' as 'array',
   },
   color: {
     default: undefined,
     description:
       'Forces test results output color highlighting (even if ' +
       'stdout is not a TTY). Set to false if you would like to have no colors.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   colors: {
     default: undefined,
     description: 'Alias for `--color`.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   config: {
     alias: 'c',
@@ -180,42 +178,44 @@ export const options = {
       'and execute tests. If no rootDir is set in the config, the directory ' +
       'containing the config file is assumed to be the rootDir for the project.' +
       'This can also be a JSON encoded value which Jest will use as configuration.',
-    type: 'string',
+    type: 'string' as 'string',
   },
   coverage: {
     default: undefined,
     description:
       'Indicates that test coverage information should be ' +
       'collected and reported in the output.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   coverageDirectory: {
     description: 'The directory where Jest should output its coverage files.',
-    type: 'string',
+    type: 'string' as 'string',
   },
   coveragePathIgnorePatterns: {
     description:
       'An array of regexp pattern strings that are matched ' +
       'against all file paths before executing the test. If the file path' +
       'matches any of the patterns, coverage information will be skipped.',
-    type: 'array',
+    string: true as true,
+    type: 'array' as 'array',
   },
   coverageReporters: {
     description:
       'A list of reporter names that Jest uses when writing ' +
       'coverage reports. Any istanbul reporter can be used.',
-    type: 'array',
+    string: true as true,
+    type: 'array' as 'array',
   },
   coverageThreshold: {
     description:
       'A JSON string with which will be used to configure ' +
       'minimum threshold enforcement for coverage results',
-    type: 'string',
+    type: 'string' as 'string',
   },
   debug: {
     default: undefined,
     description: 'Print debugging info about your jest config.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   detectLeaks: {
     default: false,
@@ -223,32 +223,32 @@ export const options = {
       '**EXPERIMENTAL**: Detect memory leaks in tests. After executing a ' +
       'test, it will try to garbage collect the global object used, and fail ' +
       'if it was leaked',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   detectOpenHandles: {
     default: false,
     description:
       'Print out remaining open handles preventing Jest from exiting at the ' +
       'end of a test run.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   env: {
     description:
       'The test environment used for all tests. This can point to ' +
       'any file or node module. Examples: `jsdom`, `node` or ' +
       '`path/to/my-environment.js`',
-    type: 'string',
+    type: 'string' as 'string',
   },
   errorOnDeprecated: {
     default: false,
     description: 'Make calling deprecated APIs throw helpful error messages.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   expand: {
     alias: 'e',
     default: undefined,
     description: 'Use this flag to show full diffs instead of a patch.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   filter: {
     default: undefined,
@@ -257,7 +257,7 @@ export const options = {
       'a list of tests which can be manipulated to exclude tests from ' +
       'running. Especially useful when used in conjunction with a testing ' +
       'infrastructure to filter known broken tests.',
-    type: 'string',
+    type: 'string' as 'string',
   },
   findRelatedTests: {
     default: undefined,
@@ -265,7 +265,7 @@ export const options = {
       'Find related tests for a list of source files that were ' +
       'passed in as arguments. Useful for pre-commit hook integration to run ' +
       'the minimal amount of tests necessary.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   forceExit: {
     default: undefined,
@@ -273,44 +273,44 @@ export const options = {
       'Force Jest to exit after all tests have completed running. ' +
       'This is useful when resources set up by test code cannot be ' +
       'adequately cleaned up.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   globalSetup: {
     description: 'The path to a module that runs before All Tests.',
-    type: 'string',
+    type: 'string' as 'string',
   },
   globalTeardown: {
     description: 'The path to a module that runs after All Tests.',
-    type: 'string',
+    type: 'string' as 'string',
   },
   globals: {
     description:
       'A JSON string with map of global variables that need ' +
       'to be available in all test environments.',
-    type: 'string',
+    type: 'string' as 'string',
   },
   haste: {
     description:
       'A JSON string with map of variables for the haste module system',
-    type: 'string',
+    type: 'string' as 'string',
   },
   init: {
     description: 'Generate a basic configuration file',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   json: {
     default: undefined,
     description:
       'Prints the test results in JSON. This mode will send all ' +
       'other test output and user messages to stderr.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   lastCommit: {
     default: undefined,
     description:
       'Run all tests affected by file changes in the last commit made. ' +
       'Behaves similarly to `--onlyChanged`.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   listTests: {
     default: false,
@@ -318,7 +318,7 @@ export const options = {
       'Lists all tests Jest will run given the arguments and ' +
       'exits. Most useful in a CI system together with `--findRelatedTests` ' +
       'to determine the tests Jest will run based on specific files',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   logHeapUsage: {
     default: undefined,
@@ -326,21 +326,21 @@ export const options = {
       'Logs the heap usage after every test. Useful to debug ' +
       'memory leaks. Use together with `--runInBand` and `--expose-gc` in ' +
       'node.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   mapCoverage: {
     default: undefined,
     description:
       'Maps code coverage reports against original source code ' +
       'when transformers supply source maps.\n\nDEPRECATED',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   maxConcurrency: {
     default: 5,
     description:
       'Specifies the maximum number of tests that are allowed to run' +
       'concurrently. This only affects tests using `test.concurrent`.',
-    type: 'number',
+    type: 'number' as 'number',
   },
   maxWorkers: {
     alias: 'w',
@@ -349,56 +349,60 @@ export const options = {
       'will spawn for running tests. This defaults to the number of the ' +
       'cores available on your machine. (its usually best not to override ' +
       'this default)',
-    type: 'number',
+    type: 'number' as 'number',
   },
   moduleDirectories: {
     description:
       'An array of directory names to be searched recursively ' +
       "up from the requiring module's location.",
-    type: 'array',
+    string: true as true,
+    type: 'array' as 'array',
   },
   moduleFileExtensions: {
     description:
       'An array of file extensions your modules use. If you ' +
       'require modules without specifying a file extension, these are the ' +
       'extensions Jest will look for. ',
-    type: 'array',
+    string: true as true,
+    type: 'array' as 'array',
   },
   moduleNameMapper: {
     description:
       'A JSON string with a map from regular expressions to ' +
       'module names that allow to stub out resources, like images or ' +
       'styles with a single module',
-    type: 'string',
+    type: 'string' as 'string',
   },
   modulePathIgnorePatterns: {
     description:
       'An array of regexp pattern strings that are matched ' +
       'against all module paths before those paths are to be considered ' +
       '"visible" to the module loader.',
-    type: 'array',
+    string: true as true,
+    type: 'array' as 'array',
   },
   modulePaths: {
     description:
       'An alternative API to setting the NODE_PATH env variable, ' +
       'modulePaths is an array of absolute paths to additional locations to ' +
       'search when resolving modules.',
-    type: 'array',
+    string: true as true,
+    type: 'array' as 'array',
   },
   noStackTrace: {
     default: undefined,
     description: 'Disables stack trace in test results output',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   notify: {
     default: undefined,
     description: 'Activates notifications for test results.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   notifyMode: {
     default: 'failure-change',
     description: 'Specifies when notifications will appear for test results.',
-    type: 'string',
+    type: 'string' as 'string',
   },
   onlyChanged: {
     alias: 'o',
@@ -407,81 +411,84 @@ export const options = {
       'Attempts to identify which tests to run based on which ' +
       "files have changed in the current repository. Only works if you're " +
       'running tests in a git or hg repository at the moment.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   onlyFailures: {
     alias: 'f',
     default: undefined,
     description: 'Run tests that failed in the previous execution.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   outputFile: {
     description:
       'Write test results to a file when the --json option is ' +
       'also specified.',
-    type: 'string',
+    type: 'string' as 'string',
   },
   passWithNoTests: {
     default: false,
     description:
       'Will not fail if no tests are found (for example while using `--testPathPattern`.)',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   preset: {
     description: "A preset that is used as a base for Jest's configuration.",
-    type: 'string',
+    type: 'string' as 'string',
   },
   prettierPath: {
     default: undefined,
     description: 'The path to the "prettier" module used for inline snapshots.',
-    type: 'string',
+    type: 'string' as 'string',
   },
   projects: {
     description:
       'A list of projects that use Jest to run all tests of all ' +
       'projects in a single instance of Jest.',
-    type: 'array',
+    string: true as true,
+    type: 'array' as 'array',
   },
   reporters: {
     description: 'A list of custom reporters for the test suite.',
-    type: 'array',
+    string: true as true,
+    type: 'array' as 'array',
   },
   resetMocks: {
     default: undefined,
     description:
       'Automatically reset mock state between every test. ' +
       'Equivalent to calling jest.resetAllMocks() between each test.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   resetModules: {
     default: undefined,
     description:
       'If enabled, the module registry for every test file will ' +
       'be reset before running each individual test.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   resolver: {
     description: 'A JSON string which allows the use of a custom resolver.',
-    type: 'string',
+    type: 'string' as 'string',
   },
   restoreMocks: {
     default: undefined,
     description:
       'Automatically restore mock state and implementation between every test. ' +
       'Equivalent to calling jest.restoreAllMocks() between each test.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   rootDir: {
     description:
       'The root directory that Jest should scan for tests and ' +
       'modules within.',
-    type: 'string',
+    type: 'string' as 'string',
   },
   roots: {
     description:
       'A list of paths to directories that Jest should use to ' +
       'search for files in.',
-    type: 'array',
+    string: true as true,
+    type: 'array' as 'array',
   },
   runInBand: {
     alias: 'i',
@@ -491,7 +498,7 @@ export const options = {
       'creating a worker pool of child processes that run tests). This ' +
       'is sometimes useful for debugging, but such use cases are pretty ' +
       'rare.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   runTestsByPath: {
     default: false,
@@ -499,136 +506,145 @@ export const options = {
       'Used when provided patterns are exact file paths. This avoids ' +
       'converting them into a regular expression and matching it against ' +
       'every single file.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   runner: {
     description:
       "Allows to use a custom runner instead of Jest's default test runner.",
-    type: 'string',
+    type: 'string' as 'string',
   },
   setupFiles: {
     description:
       'A list of paths to modules that run some code to configure or ' +
       'set up the testing environment before each test. ',
-    type: 'array',
+    string: true as true,
+    type: 'array' as 'array',
   },
   setupFilesAfterEnv: {
     description:
       'A list of paths to modules that run some code to configure or ' +
       'set up the testing framework before each test ',
-    type: 'array',
+    string: true as true,
+    type: 'array' as 'array',
   },
   showConfig: {
     default: undefined,
     description: 'Print your jest config and then exits.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   silent: {
     default: undefined,
     description: 'Prevent tests from printing messages through the console.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   skipFilter: {
     default: undefined,
     description:
       'Disables the filter provided by --filter. Useful for CI jobs, or ' +
       'local enforcement when fixing tests.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   snapshotSerializers: {
     description:
       'A list of paths to snapshot serializer modules Jest should ' +
       'use for snapshot testing.',
-    type: 'array',
+    string: true as true,
+    type: 'array' as 'array',
   },
   testEnvironment: {
     description: 'Alias for --env',
-    type: 'string',
+    type: 'string' as 'string',
   },
   testEnvironmentOptions: {
     description:
       'Test environment options that will be passed to the testEnvironment. ' +
       'The relevant options depend on the environment.',
-    type: 'string', // Object
+    type: 'string' as 'string', // Object
   },
   testFailureExitCode: {
     description: 'Exit code of `jest` command if the test run failed',
-    type: 'string', // number
+    type: 'string' as 'string', // number
   },
   testLocationInResults: {
     default: false,
     description: 'Add `location` information to the test results',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   testMatch: {
     description: 'The glob patterns Jest uses to detect test files.',
-    type: 'array',
+    string: true as true,
+    type: 'array' as 'array',
   },
   testNamePattern: {
     alias: 't',
     description: 'Run only tests with a name that matches the regex pattern.',
-    type: 'string',
+    type: 'string' as 'string',
   },
   testPathIgnorePatterns: {
     description:
       'An array of regexp pattern strings that are matched ' +
       'against all test paths before executing the test. If the test path ' +
       'matches any of the patterns, it will be skipped.',
-    type: 'array',
+    string: true as true,
+    type: 'array' as 'array',
   },
   testPathPattern: {
     description:
       'A regexp pattern string that is matched against all tests ' +
       'paths before executing the test.',
-    type: 'array',
+    string: true as true,
+    type: 'array' as 'array',
   },
   testRegex: {
     description:
       'A string or array of string regexp patterns that Jest uses to detect test files.',
-    type: 'array',
+    string: true as true,
+    type: 'array' as 'array',
   },
   testResultsProcessor: {
     description:
       'Allows the use of a custom results processor. ' +
       'This processor must be a node module that exports ' +
       'a function expecting as the first argument the result object.',
-    type: 'string',
+    type: 'string' as 'string',
   },
   testRunner: {
     description:
       'Allows to specify a custom test runner. The default is ' +
       ' `jasmine2`. A path to a custom test runner can be provided: ' +
       '`<rootDir>/path/to/testRunner.js`.',
-    type: 'string',
+    type: 'string' as 'string',
   },
   testURL: {
     description: 'This option sets the URL for the jsdom environment.',
-    type: 'string',
+    type: 'string' as 'string',
   },
   timers: {
     description:
       'Setting this value to fake allows the use of fake timers ' +
       'for functions such as setTimeout.',
-    type: 'string',
+    type: 'string' as 'string',
   },
   transform: {
     description:
       'A JSON string which maps from regular expressions to paths ' +
       'to transformers.',
-    type: 'string',
+    type: 'string' as 'string',
   },
   transformIgnorePatterns: {
     description:
       'An array of regexp pattern strings that are matched ' +
       'against all source file paths before transformation.',
-    type: 'array',
+    string: true as true,
+    type: 'array' as 'array',
   },
   unmockedModulePathPatterns: {
     description:
       'An array of regexp pattern strings that are matched ' +
       'against all modules before the module loader will automatically ' +
       'return a mock for them.',
-    type: 'array',
+    string: true as true,
+    type: 'array' as 'array',
   },
   updateSnapshot: {
     alias: 'u',
@@ -638,24 +654,24 @@ export const options = {
       'Can be used together with a test suite pattern or with ' +
       '`--testNamePattern` to re-record snapshot for test matching ' +
       'the pattern',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   useStderr: {
     default: undefined,
     description: 'Divert all output to stderr.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   verbose: {
     default: undefined,
     description:
       'Display individual test results with the test suite hierarchy.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   version: {
     alias: 'v',
     default: undefined,
     description: 'Print the version and exit',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   watch: {
     default: undefined,
@@ -663,7 +679,7 @@ export const options = {
       'Watch files for changes and rerun tests related to ' +
       'changed files. If you want to re-run all tests when a file has ' +
       'changed, use the `--watchAll` option.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   watchAll: {
     default: undefined,
@@ -671,20 +687,21 @@ export const options = {
       'Watch files for changes and rerun all tests. If you want ' +
       'to re-run only the tests related to the changed files, use the ' +
       '`--watch` option.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
   watchPathIgnorePatterns: {
     description:
       'An array of regexp pattern strings that are matched ' +
       'against all paths before trigger test re-run in watch mode. ' +
       'If the test path matches any of the patterns, it will be skipped.',
-    type: 'array',
+    string: true as true,
+    type: 'array' as 'array',
   },
   watchman: {
     default: undefined,
     description:
       'Whether to use watchman for file crawling. Disable using ' +
       '--no-watchman.',
-    type: 'boolean',
+    type: 'boolean' as 'boolean',
   },
 };
diff --git a/packages/jest-cli/src/cli/index.js b/packages/jest-cli/src/cli/index.ts
similarity index 75%
rename from packages/jest-cli/src/cli/index.js
rename to packages/jest-cli/src/cli/index.ts
index 910cc7f10fa8..a09878ba9dc5 100644
--- a/packages/jest-cli/src/cli/index.js
+++ b/packages/jest-cli/src/cli/index.ts
@@ -3,32 +3,25 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {AggregatedResult} from 'types/TestResult';
-import type {Argv} from 'types/Argv';
-import type {GlobalConfig, Path} from 'types/Config';
-
 import path from 'path';
+import {Config, TestResult} from '@jest/types';
 import {clearLine} from 'jest-util';
 import {validateCLIOptions} from 'jest-validate';
 import {deprecationEntries} from 'jest-config';
 import {runCLI} from '@jest/core';
-import * as args from './args';
 import chalk from 'chalk';
 import exit from 'exit';
 import yargs from 'yargs';
 import {sync as realpath} from 'realpath-native';
 import init from '../init';
+import getVersion from '../version';
+import * as args from './args';
 
-import {version as VERSION} from '../../package.json';
-
-export async function run(maybeArgv?: Argv, project?: Path) {
+export async function run(maybeArgv?: Array<string>, project?: Config.Path) {
   try {
-    // $FlowFixMe:`allow reduced return
-    const argv: Argv = buildArgv(maybeArgv);
+    const argv: Config.Argv = buildArgv(maybeArgv);
 
     if (argv.init) {
       await init();
@@ -48,12 +41,14 @@ export async function run(maybeArgv?: Argv, project?: Path) {
   }
 }
 
-export const buildArgv = (maybeArgv: ?Argv) => {
+export const buildArgv = (maybeArgv?: Array<string>): Config.Argv => {
   const version =
-    VERSION + (__dirname.includes(`packages${path.sep}jest-cli`) ? '-dev' : '');
+    getVersion() +
+    (__dirname.includes(`packages${path.sep}jest-cli`) ? '-dev' : '');
 
-  const rawArgv: Argv | string[] = maybeArgv || process.argv.slice(2);
-  const argv: Argv = yargs(rawArgv)
+  const rawArgv: Config.Argv | Array<string> =
+    maybeArgv || process.argv.slice(2);
+  const argv: Config.Argv = yargs(rawArgv)
     .usage(args.usage)
     .version(version)
     .alias('help', 'h')
@@ -71,16 +66,21 @@ export const buildArgv = (maybeArgv: ?Argv) => {
   );
 
   // strip dashed args
-  return Object.keys(argv).reduce((result, key) => {
-    if (!key.includes('-')) {
-      // $FlowFixMe:`allow reduced return
-      result[key] = argv[key];
-    }
-    return result;
-  }, {});
+  return Object.keys(argv).reduce(
+    (result, key) => {
+      if (!key.includes('-')) {
+        result[key] = argv[key];
+      }
+      return result;
+    },
+    {} as Config.Argv,
+  );
 };
 
-const getProjectListFromCLIArgs = (argv, project: ?Path) => {
+const getProjectListFromCLIArgs = (
+  argv: Config.Argv,
+  project?: Config.Path,
+) => {
   const projects = argv.projects ? argv.projects : [];
 
   if (project) {
@@ -104,8 +104,8 @@ const getProjectListFromCLIArgs = (argv, project: ?Path) => {
 };
 
 const readResultsAndExit = (
-  result: ?AggregatedResult,
-  globalConfig: GlobalConfig,
+  result: TestResult.AggregatedResult | null,
+  globalConfig: Config.GlobalConfig,
 ) => {
   const code = !result || result.success ? 0 : globalConfig.testFailureExitCode;
 
@@ -140,7 +140,6 @@ const readResultsAndExit = (
               '`--detectOpenHandles` to troubleshoot this issue.',
           ),
       );
-      // $FlowFixMe: `unref` exists in Node
     }, 1000).unref();
   }
 };
diff --git a/packages/jest-cli/src/index.js b/packages/jest-cli/src/index.ts
similarity index 97%
rename from packages/jest-cli/src/index.js
rename to packages/jest-cli/src/index.ts
index 7ebc603595c4..956d00196105 100644
--- a/packages/jest-cli/src/index.js
+++ b/packages/jest-cli/src/index.ts
@@ -3,8 +3,6 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
 // TODO: remove exports for the next major
diff --git a/packages/jest-cli/src/init/__tests__/__snapshots__/modify_package_json.test.js.snap b/packages/jest-cli/src/init/__tests__/__snapshots__/modify_package_json.test.ts.snap
similarity index 100%
rename from packages/jest-cli/src/init/__tests__/__snapshots__/modify_package_json.test.js.snap
rename to packages/jest-cli/src/init/__tests__/__snapshots__/modify_package_json.test.ts.snap
diff --git a/packages/jest-cli/src/init/__tests__/init.test.js b/packages/jest-cli/src/init/__tests__/init.test.js
index d10629e6153a..65a8128b36b6 100644
--- a/packages/jest-cli/src/init/__tests__/init.test.js
+++ b/packages/jest-cli/src/init/__tests__/init.test.js
@@ -3,8 +3,6 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
 /* eslint-disable no-eval */
diff --git a/packages/jest-cli/src/init/__tests__/modify_package_json.test.js b/packages/jest-cli/src/init/__tests__/modify_package_json.test.ts
similarity index 97%
rename from packages/jest-cli/src/init/__tests__/modify_package_json.test.js
rename to packages/jest-cli/src/init/__tests__/modify_package_json.test.ts
index aa2f8f4641f4..8c7dad5a0bef 100644
--- a/packages/jest-cli/src/init/__tests__/modify_package_json.test.js
+++ b/packages/jest-cli/src/init/__tests__/modify_package_json.test.ts
@@ -3,7 +3,6 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
  */
 
 import modifyPackageJson from '../modify_package_json';
@@ -13,7 +12,7 @@ test('should remove jest config if exists', () => {
     modifyPackageJson({
       projectPackageJson: {
         jest: {
-          coverage: true,
+          collectCoverage: true,
         },
       },
       shouldModifyScripts: true,
diff --git a/packages/jest-cli/src/init/constants.js b/packages/jest-cli/src/init/constants.ts
similarity index 96%
rename from packages/jest-cli/src/init/constants.js
rename to packages/jest-cli/src/init/constants.ts
index 29044effbaeb..8ebd1eecd72a 100644
--- a/packages/jest-cli/src/init/constants.js
+++ b/packages/jest-cli/src/init/constants.ts
@@ -3,8 +3,6 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
 export const PACKAGE_JSON = 'package.json';
diff --git a/packages/jest-cli/src/init/errors.js b/packages/jest-cli/src/init/errors.ts
similarity index 70%
rename from packages/jest-cli/src/init/errors.js
rename to packages/jest-cli/src/init/errors.ts
index 242066f4d3dc..2c85b6585a7f 100644
--- a/packages/jest-cli/src/init/errors.js
+++ b/packages/jest-cli/src/init/errors.ts
@@ -3,32 +3,23 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
 export class NotFoundPackageJsonError extends Error {
-  name: string;
-  message: string;
-
   constructor(rootDir: string) {
-    super();
+    super(`Could not find a "package.json" file in ${rootDir}`);
     this.name = '';
-    this.message = `Could not find a "package.json" file in ${rootDir}`;
     Error.captureStackTrace(this, () => {});
   }
 }
 
 export class MalformedPackageJsonError extends Error {
-  name: string;
-  message: string;
-
   constructor(packageJsonPath: string) {
-    super();
-    this.name = '';
-    this.message =
+    super(
       `There is malformed json in ${packageJsonPath}\n` +
-      'Fix it, and then run "jest --init"';
+        'Fix it, and then run "jest --init"',
+    );
+    this.name = '';
     Error.captureStackTrace(this, () => {});
   }
 }
diff --git a/packages/jest-cli/src/init/generate_config_file.js b/packages/jest-cli/src/init/generate_config_file.ts
similarity index 70%
rename from packages/jest-cli/src/init/generate_config_file.js
rename to packages/jest-cli/src/init/generate_config_file.ts
index 0732a08c6d5f..961c4610ce71 100644
--- a/packages/jest-cli/src/init/generate_config_file.js
+++ b/packages/jest-cli/src/init/generate_config_file.ts
@@ -3,15 +3,14 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
+import {Config} from '@jest/types';
 import {defaults, descriptions} from 'jest-config';
 
 const stringifyOption = (
-  option: string,
-  map: Object,
+  option: keyof Config.InitialOptions,
+  map: Partial<Config.InitialOptions>,
   linePrefix: string = '',
 ): string => {
   const optionDescription = `  // ${descriptions[option]}`;
@@ -32,10 +31,10 @@ const stringifyOption = (
   );
 };
 
-const generateConfigFile = (results: {[string]: boolean}): string => {
+const generateConfigFile = (results: {[key: string]: unknown}): string => {
   const {coverage, clearMocks, environment} = results;
 
-  const overrides: Object = {};
+  const overrides: Record<string, any> = {};
 
   if (coverage) {
     Object.assign(overrides, {
@@ -55,15 +54,21 @@ const generateConfigFile = (results: {[string]: boolean}): string => {
     });
   }
 
-  const overrideKeys: Array<string> = Object.keys(overrides);
+  const overrideKeys = Object.keys(overrides) as Array<
+    keyof Config.InitialOptions
+  >;
 
   const properties: Array<string> = [];
 
   for (const option in descriptions) {
-    if (overrideKeys.includes(option)) {
-      properties.push(stringifyOption(option, overrides));
+    const opt = option as keyof typeof descriptions;
+
+    if (overrideKeys.includes(opt)) {
+      properties.push(stringifyOption(opt, overrides));
     } else {
-      properties.push(stringifyOption(option, defaults, '// '));
+      properties.push(
+        stringifyOption(opt, defaults as Config.InitialOptions, '// '),
+      );
     }
   }
 
diff --git a/packages/jest-cli/src/init/index.js b/packages/jest-cli/src/init/index.ts
similarity index 92%
rename from packages/jest-cli/src/init/index.js
rename to packages/jest-cli/src/init/index.ts
index 68dd9f4fa640..7df3da704f5c 100644
--- a/packages/jest-cli/src/init/index.js
+++ b/packages/jest-cli/src/init/index.ts
@@ -3,13 +3,11 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import chalk from 'chalk';
 import fs from 'fs';
 import path from 'path';
+import chalk from 'chalk';
 import prompts from 'prompts';
 import {sync as realpath} from 'realpath-native';
 import defaultQuestions, {testScriptQuestion} from './questions';
@@ -17,12 +15,13 @@ import {NotFoundPackageJsonError, MalformedPackageJsonError} from './errors';
 import {PACKAGE_JSON, JEST_CONFIG} from './constants';
 import generateConfigFile from './generate_config_file';
 import modifyPackageJson from './modify_package_json';
+import {ProjectPackageJson} from './types';
 
 type PromptsResults = {
-  clearMocks: boolean,
-  coverage: boolean,
-  environment: boolean,
-  scripts: boolean,
+  clearMocks: boolean;
+  coverage: boolean;
+  environment: boolean;
+  scripts: boolean;
 };
 
 export default async (rootDir: string = realpath(process.cwd())) => {
@@ -37,7 +36,7 @@ export default async (rootDir: string = realpath(process.cwd())) => {
   const questions = defaultQuestions.slice(0);
   let hasJestProperty: boolean = false;
   let hasJestConfig: boolean = false;
-  let projectPackageJson: ?Object;
+  let projectPackageJson: ProjectPackageJson;
 
   try {
     projectPackageJson = JSON.parse(
@@ -89,6 +88,7 @@ export default async (rootDir: string = realpath(process.cwd())) => {
 
   let promptAborted: boolean = false;
 
+  // @ts-ignore: Return type cannot be object - faulty typings
   const results: PromptsResults = await prompts(questions, {
     onCancel: () => {
       promptAborted = true;
diff --git a/packages/jest-cli/src/init/modify_package_json.js b/packages/jest-cli/src/init/modify_package_json.ts
similarity index 83%
rename from packages/jest-cli/src/init/modify_package_json.js
rename to packages/jest-cli/src/init/modify_package_json.ts
index 6dc6172872bb..c38835b00270 100644
--- a/packages/jest-cli/src/init/modify_package_json.js
+++ b/packages/jest-cli/src/init/modify_package_json.ts
@@ -3,17 +3,16 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
+import {ProjectPackageJson} from './types';
+
 const modifyPackageJson = ({
   projectPackageJson,
   shouldModifyScripts,
-  hasJestProperty,
 }: {
-  projectPackageJson: Object,
-  shouldModifyScripts: boolean,
+  projectPackageJson: ProjectPackageJson;
+  shouldModifyScripts: boolean;
 }): string => {
   if (shouldModifyScripts) {
     projectPackageJson.scripts
diff --git a/packages/jest-cli/src/init/questions.js b/packages/jest-cli/src/init/questions.ts
similarity index 78%
rename from packages/jest-cli/src/init/questions.js
rename to packages/jest-cli/src/init/questions.ts
index 5e7c829b7f10..d9179b2d1cb5 100644
--- a/packages/jest-cli/src/init/questions.js
+++ b/packages/jest-cli/src/init/questions.ts
@@ -3,19 +3,11 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-type Question = {|
-  initial?: boolean | number,
-  message: string,
-  name: string,
-  type: string,
-  choices?: Array<{title: string, value: string}>,
-|};
+import {PromptObject} from 'prompts';
 
-const defaultQuestions: Array<Question> = [
+const defaultQuestions: Array<PromptObject> = [
   {
     choices: [
       {title: 'node', value: 'node'},
@@ -42,7 +34,7 @@ const defaultQuestions: Array<Question> = [
 
 export default defaultQuestions;
 
-export const testScriptQuestion: Question = {
+export const testScriptQuestion: PromptObject = {
   initial: true,
   message:
     'Would you like to use Jest when running "test" script in "package.json"?',
diff --git a/packages/jest-cli/src/init/types.ts b/packages/jest-cli/src/init/types.ts
new file mode 100644
index 000000000000..81184fb1aabd
--- /dev/null
+++ b/packages/jest-cli/src/init/types.ts
@@ -0,0 +1,13 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {Config} from '@jest/types';
+
+export type ProjectPackageJson = {
+  jest?: Partial<Config.InitialOptions>;
+  scripts?: {[key: string]: string};
+};
diff --git a/packages/jest-cli/src/version.js b/packages/jest-cli/src/version.ts
similarity index 69%
rename from packages/jest-cli/src/version.js
rename to packages/jest-cli/src/version.ts
index 23a05d19add1..5d778a274253 100644
--- a/packages/jest-cli/src/version.js
+++ b/packages/jest-cli/src/version.ts
@@ -3,12 +3,10 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import {version as VERSION} from '../package.json';
+const {version: VERSION} = require('../package.json');
 
-export default function getVersion() {
+export default function getVersion(): string {
   return VERSION;
 }
diff --git a/packages/jest-cli/tsconfig.json b/packages/jest-cli/tsconfig.json
new file mode 100644
index 000000000000..a7ff1e06b7d1
--- /dev/null
+++ b/packages/jest-cli/tsconfig.json
@@ -0,0 +1,14 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "rootDir": "src",
+    "outDir": "build"
+  },
+  "references": [
+    {"path": "../jest-core"},
+    {"path": "../jest-config"},
+    {"path": "../jest-types"},
+    {"path": "../jest-util"},
+    {"path": "../jest-validate"}
+  ]
+}
diff --git a/packages/jest-config/src/Deprecated.ts b/packages/jest-config/src/Deprecated.ts
index 8ad752842d2a..898d9fe96deb 100644
--- a/packages/jest-config/src/Deprecated.ts
+++ b/packages/jest-config/src/Deprecated.ts
@@ -74,4 +74,4 @@ export default {
 
   Please update your configuration.
   `,
-};
+} as Record<string, Function>;
diff --git a/packages/jest-config/src/normalize.ts b/packages/jest-config/src/normalize.ts
index d1ed515126a3..e43bd523af8a 100644
--- a/packages/jest-config/src/normalize.ts
+++ b/packages/jest-config/src/normalize.ts
@@ -829,7 +829,7 @@ export default function normalize(
 
   newOptions.nonFlagArgs = argv._;
   newOptions.testPathPattern = buildTestPathPattern(argv);
-  newOptions.json = argv.json;
+  newOptions.json = !!argv.json;
 
   newOptions.testFailureExitCode = parseInt(
     (newOptions.testFailureExitCode as unknown) as string,
diff --git a/packages/jest-config/src/setFromArgv.ts b/packages/jest-config/src/setFromArgv.ts
index f1ca92ed20be..8ae4aa11c4b1 100644
--- a/packages/jest-config/src/setFromArgv.ts
+++ b/packages/jest-config/src/setFromArgv.ts
@@ -39,8 +39,9 @@ export default function setFromArgv(
         case 'moduleNameMapper':
         case 'transform':
         case 'haste':
-          if (isJSONString(argv[key])) {
-            options[key] = JSON.parse(argv[key]);
+          const str = argv[key];
+          if (isJSONString(str)) {
+            options[key] = JSON.parse(str);
           }
           break;
         default:
diff --git a/packages/jest-config/src/utils.ts b/packages/jest-config/src/utils.ts
index fb3b139f75b6..ca7c5d9d0047 100644
--- a/packages/jest-config/src/utils.ts
+++ b/packages/jest-config/src/utils.ts
@@ -217,8 +217,9 @@ export const getRunner = (
     rootDir,
   });
 
-export const isJSONString = (text?: string) =>
-  text &&
+type JSONString = string & {readonly $$type: never}; // newtype
+export const isJSONString = (text?: JSONString | string): text is JSONString =>
+  text != null &&
   typeof text === 'string' &&
   text.startsWith('{') &&
   text.endsWith('}');
diff --git a/packages/jest-core/src/SearchSource.ts b/packages/jest-core/src/SearchSource.ts
index 5c1992b55d94..ee28ca92bc8b 100644
--- a/packages/jest-core/src/SearchSource.ts
+++ b/packages/jest-core/src/SearchSource.ts
@@ -128,7 +128,7 @@ export default class SearchSource {
 
     const testCasesKeys = Object.keys(testCases) as Array<keyof Stats>;
     data.tests = allPaths.filter(test =>
-      testCasesKeys.reduce((flag, key) => {
+      testCasesKeys.reduce<boolean>((flag, key) => {
         const {stats} = data;
         if (testCases[key](test.path)) {
           stats[key] = stats[key] === undefined ? 1 : stats[key] + 1;
diff --git a/packages/jest-types/src/Config.ts b/packages/jest-types/src/Config.ts
index 45cea095571d..d0b958ee9e44 100644
--- a/packages/jest-types/src/Config.ts
+++ b/packages/jest-types/src/Config.ts
@@ -363,92 +363,90 @@ export type ProjectConfig = {
   unmockedModulePathPatterns: Array<string> | null | undefined;
 };
 
-export type Argv = Arguments<{
-  all: boolean;
-  automock: boolean;
-  bail: boolean | number;
-  browser: boolean;
-  cache: boolean;
-  cacheDirectory: string;
-  changedFilesWithAncestor: boolean;
-  changedSince: string;
-  ci: boolean;
-  clearCache: boolean;
-  clearMocks: boolean;
-  collectCoverage: boolean;
-  collectCoverageFrom: Array<string>;
-  collectCoverageOnlyFrom: Array<string>;
-  config: string;
-  coverage: boolean;
-  coverageDirectory: string;
-  coveragePathIgnorePatterns: Array<string>;
-  coverageReporters: Array<string>;
-  coverageThreshold: string;
-  debug: boolean;
-  env: string;
-  expand: boolean;
-  findRelatedTests: boolean;
-  forceExit: boolean;
-  globals: string;
-  globalSetup: string | null | undefined;
-  globalTeardown: string | null | undefined;
-  h: boolean;
-  haste: string;
-  help: boolean;
-  init: boolean;
-  json: boolean;
-  lastCommit: boolean;
-  logHeapUsage: boolean;
-  maxWorkers: number;
-  moduleDirectories: Array<string>;
-  moduleFileExtensions: Array<string>;
-  moduleLoader: string;
-  moduleNameMapper: string;
-  modulePathIgnorePatterns: Array<string>;
-  modulePaths: Array<string>;
-  name: string;
-  noSCM: boolean;
-  noStackTrace: boolean;
-  notify: boolean;
-  notifyMode: string;
-  onlyChanged: boolean;
-  outputFile: string;
-  preset: string | null | undefined;
-  projects: Array<string>;
-  prettierPath: string | null | undefined;
-  replname: string | null | undefined;
-  resetMocks: boolean;
-  resetModules: boolean;
-  resolver: string | null | undefined;
-  restoreMocks: boolean;
-  rootDir: string;
-  roots: Array<string>;
-  runInBand: boolean;
-  setupFiles: Array<string>;
-  setupFilesAfterEnv: Array<string>;
-  showConfig: boolean;
-  silent: boolean;
-  snapshotSerializers: Array<string>;
-  testEnvironment: string;
-  testFailureExitCode: string | null | undefined;
-  testMatch: Array<string>;
-  testNamePattern: string;
-  testPathIgnorePatterns: Array<string>;
-  testPathPattern: Array<string>;
-  testRegex: string | Array<string>;
-  testResultsProcessor: string | null | undefined;
-  testRunner: string;
-  testURL: string;
-  timers: 'real' | 'fake';
-  transform: string;
-  transformIgnorePatterns: Array<string>;
-  unmockedModulePathPatterns: Array<string> | null | undefined;
-  updateSnapshot: boolean;
-  useStderr: boolean;
-  verbose: boolean | null | undefined;
-  version: boolean;
-  watch: boolean;
-  watchAll: boolean;
-  watchman: boolean;
-  watchPathIgnorePatterns: Array<string>;
-}>;
+export type Argv = Arguments<
+  Partial<{
+    all: boolean;
+    automock: boolean;
+    bail: boolean | number;
+    browser: boolean;
+    cache: boolean;
+    cacheDirectory: string;
+    changedFilesWithAncestor: boolean;
+    changedSince: string;
+    ci: boolean;
+    clearCache: boolean;
+    clearMocks: boolean;
+    collectCoverage: boolean;
+    collectCoverageFrom: string;
+    collectCoverageOnlyFrom: Array<string>;
+    color: boolean;
+    colors: boolean;
+    config: string;
+    coverage: boolean;
+    coverageDirectory: string;
+    coveragePathIgnorePatterns: Array<string>;
+    coverageReporters: Array<string>;
+    coverageThreshold: string;
+    debug: boolean;
+    env: string;
+    expand: boolean;
+    findRelatedTests: boolean;
+    forceExit: boolean;
+    globals: string;
+    globalSetup: string | null | undefined;
+    globalTeardown: string | null | undefined;
+    haste: string;
+    init: boolean;
+    json: boolean;
+    lastCommit: boolean;
+    logHeapUsage: boolean;
+    maxWorkers: number;
+    moduleDirectories: Array<string>;
+    moduleFileExtensions: Array<string>;
+    moduleNameMapper: string;
+    modulePathIgnorePatterns: Array<string>;
+    modulePaths: Array<string>;
+    noStackTrace: boolean;
+    notify: boolean;
+    notifyMode: string;
+    onlyChanged: boolean;
+    outputFile: string;
+    preset: string | null | undefined;
+    projects: Array<string>;
+    prettierPath: string | null | undefined;
+    resetMocks: boolean;
+    resetModules: boolean;
+    resolver: string | null | undefined;
+    restoreMocks: boolean;
+    rootDir: string;
+    roots: Array<string>;
+    runInBand: boolean;
+    setupFiles: Array<string>;
+    setupFilesAfterEnv: Array<string>;
+    showConfig: boolean;
+    silent: boolean;
+    snapshotSerializers: Array<string>;
+    testEnvironment: string;
+    testFailureExitCode: string | null | undefined;
+    testMatch: Array<string>;
+    testNamePattern: string;
+    testPathIgnorePatterns: Array<string>;
+    testPathPattern: Array<string>;
+    testRegex: string | Array<string>;
+    testResultsProcessor: string | null | undefined;
+    testRunner: string;
+    testURL: string;
+    timers: string;
+    transform: string;
+    transformIgnorePatterns: Array<string>;
+    unmockedModulePathPatterns: Array<string> | null | undefined;
+    updateSnapshot: boolean;
+    useStderr: boolean;
+    verbose: boolean | null | undefined;
+    version: boolean;
+    watch: boolean;
+    watchAll: boolean;
+    watchman: boolean;
+    watchPathIgnorePatterns: Array<string>;
+  }>
+>;
diff --git a/packages/jest-validate/src/validateCLIOptions.ts b/packages/jest-validate/src/validateCLIOptions.ts
index 9a2e6406ddbb..a4962ed2dc74 100644
--- a/packages/jest-validate/src/validateCLIOptions.ts
+++ b/packages/jest-validate/src/validateCLIOptions.ts
@@ -8,6 +8,8 @@
 import {Config} from '@jest/types';
 import chalk from 'chalk';
 import camelcase from 'camelcase';
+// eslint-disable-next-line import/no-extraneous-dependencies
+import {Options} from 'yargs';
 import {createDidYouMeanMessage, format, ValidationError} from './utils';
 import {deprecationWarning} from './deprecated';
 import defaultConfig from './defaultConfig';
@@ -63,15 +65,16 @@ const logDeprecatedOptions = (
 export default function validateCLIOptions(
   argv: Config.Argv,
   options: {
-    [s: string]: {alias?: string};
     deprecationEntries: DeprecatedOptions;
+    [s: string]: Options;
   },
   rawArgv: Array<string> = [],
 ) {
   const yargsSpecialOptions = ['$0', '_', 'help', 'h'];
   const deprecationEntries = options.deprecationEntries || {};
   const allowedOptions = Object.keys(options).reduce(
-    (acc, option) => acc.add(option).add(options[option].alias || option),
+    (acc, option) =>
+      acc.add(option).add((options[option].alias as string) || option),
     new Set(yargsSpecialOptions),
   );
   const unrecognizedOptions = Object.keys(argv).filter(
@@ -89,7 +92,7 @@ export default function validateCLIOptions(
     (acc, entry) => {
       if (options[entry]) {
         acc[entry] = deprecationEntries[entry];
-        const alias = options[entry].alias;
+        const alias = options[entry].alias as string;
         if (alias) {
           acc[alias] = deprecationEntries[entry];
         }
diff --git a/packages/jest-watcher/package.json b/packages/jest-watcher/package.json
index df3bd61731ce..5d3fe4087861 100644
--- a/packages/jest-watcher/package.json
+++ b/packages/jest-watcher/package.json
@@ -6,6 +6,7 @@
   "dependencies": {
     "@jest/types": "^24.1.0",
     "@types/node": "*",
+    "@types/yargs": "^12.0.9",
     "ansi-escapes": "^3.0.0",
     "chalk": "^2.0.1",
     "jest-util": "^24.0.0",
diff --git a/packages/jest/package.json b/packages/jest/package.json
index b14020ae23a7..5099ba284447 100644
--- a/packages/jest/package.json
+++ b/packages/jest/package.json
@@ -3,6 +3,7 @@
   "description": "Delightful JavaScript Testing.",
   "version": "24.1.0",
   "main": "build/jest.js",
+  "types": "build/jest.d.ts",
   "dependencies": {
     "import-local": "^2.0.0",
     "jest-cli": "^24.1.0"
diff --git a/packages/jest/src/jest.js b/packages/jest/src/jest.ts
similarity index 87%
rename from packages/jest/src/jest.js
rename to packages/jest/src/jest.ts
index fe580071a094..f7322540629f 100644
--- a/packages/jest/src/jest.js
+++ b/packages/jest/src/jest.ts
@@ -3,10 +3,8 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
 import * as cli from 'jest-cli';
 
-module.exports = cli;
+export = cli;
diff --git a/packages/jest/tsconfig.json b/packages/jest/tsconfig.json
new file mode 100644
index 000000000000..0e089576b519
--- /dev/null
+++ b/packages/jest/tsconfig.json
@@ -0,0 +1,10 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "rootDir": "src",
+    "outDir": "build"
+  },
+  "references": [
+    {"path": "../jest-cli"}
+  ]
+}
diff --git a/yarn.lock b/yarn.lock
index d0398e7f8311..8da8658b833f 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1928,7 +1928,7 @@
   dependencies:
     "@types/node" "*"
 
-"@types/yargs@^12.0.2":
+"@types/yargs@^12.0.2", "@types/yargs@^12.0.9":
   version "12.0.9"
   resolved "https://registry.yarnpkg.com/@types/yargs/-/yargs-12.0.9.tgz#693e76a52f61a2f1e7fb48c0eef167b95ea4ffd0"
   integrity sha512-sCZy4SxP9rN2w30Hlmg5dtdRwgYQfYRiLo9usw8X9cxlf+H4FqM1xX7+sNH7NNKVdbXMJWqva7iyy+fxh/V7fA==