diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 9ae861eb9e89..e1601ea14db3 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -363,7 +363,10 @@ a package by importing from it in the TypeScript file, and then running:
 `jlpm run integrity` from the repo root.
 
 We also have scripts for creating and removing packages in `packages/`,
-`jlpm run create:package` and `jlpm run remove:package`.
+`jlpm run create:package` and `jlpm run remove:package`. When creating a package,
+if it is meant to be included in the core bundle, add the `jupyterlab: { coreDependency: true }`
+metadata to the `package.json`. Packages with `extension` or `mimeExtension` metadata
+are considered to be a core dependency unless they are explicitly marked otherwise.
 
 ## Testing Changes to External Packages
 
diff --git a/buildutils/src/ensure-repo.ts b/buildutils/src/ensure-repo.ts
index d10e2855a33f..90767aca9872 100644
--- a/buildutils/src/ensure-repo.ts
+++ b/buildutils/src/ensure-repo.ts
@@ -120,7 +120,23 @@ function ensureJupyterlab(): string[] {
     } catch (e) {
       return;
     }
-    if (data.private === true || data.name === '@jupyterlab/metapackage') {
+    // Determine whether to include the package.
+    if (!data.jupyterlab) {
+      return;
+    }
+    // Skip if explicitly marked as not a core dep.
+    if (
+      'coreDependency' in data.jupyterlab &&
+      !data.jupyterlab.coreDependency
+    ) {
+      return;
+    }
+    // Skip if it is not marked as an extension or a core dep.
+    if (
+      !data.jupyterlab.coreDependency &&
+      !data.jupyterlab.extension &&
+      !data.jupyterlab.mimeExtension
+    ) {
       return;
     }
 
diff --git a/dev_mode/package.json b/dev_mode/package.json
index c3e4cfbc0c8b..7767df23df98 100644
--- a/dev_mode/package.json
+++ b/dev_mode/package.json
@@ -16,22 +16,14 @@
     "@jupyterlab/application-extension": "^1.0.0-alpha.6",
     "@jupyterlab/apputils": "^1.0.0-alpha.6",
     "@jupyterlab/apputils-extension": "^1.0.0-alpha.6",
-    "@jupyterlab/attachments": "^1.0.0-alpha.6",
-    "@jupyterlab/cells": "^1.0.0-alpha.7",
-    "@jupyterlab/codeeditor": "^1.0.0-alpha.6",
-    "@jupyterlab/codemirror": "^1.0.0-alpha.6",
     "@jupyterlab/codemirror-extension": "^1.0.0-alpha.6",
-    "@jupyterlab/completer": "^1.0.0-alpha.6",
     "@jupyterlab/completer-extension": "^1.0.0-alpha.6",
     "@jupyterlab/console": "^1.0.0-alpha.6",
     "@jupyterlab/console-extension": "^1.0.0-alpha.6",
     "@jupyterlab/coreutils": "^3.0.0-alpha.6",
-    "@jupyterlab/csvviewer": "^1.0.0-alpha.6",
     "@jupyterlab/csvviewer-extension": "^1.0.0-alpha.7",
     "@jupyterlab/docmanager": "^1.0.0-alpha.6",
     "@jupyterlab/docmanager-extension": "^1.0.0-alpha.6",
-    "@jupyterlab/docregistry": "^1.0.0-alpha.6",
-    "@jupyterlab/documentsearch": "^1.0.0-alpha.7",
     "@jupyterlab/documentsearch-extension": "^1.0.0-alpha.8",
     "@jupyterlab/extensionmanager": "^1.0.0-alpha.6",
     "@jupyterlab/extensionmanager-extension": "^1.0.0-alpha.6",
@@ -41,38 +33,27 @@
     "@jupyterlab/fileeditor": "^1.0.0-alpha.6",
     "@jupyterlab/fileeditor-extension": "^1.0.0-alpha.6",
     "@jupyterlab/help-extension": "^1.0.0-alpha.6",
-    "@jupyterlab/htmlviewer": "^1.0.0-alpha.7",
     "@jupyterlab/htmlviewer-extension": "^1.0.0-alpha.7",
     "@jupyterlab/imageviewer": "^1.0.0-alpha.6",
     "@jupyterlab/imageviewer-extension": "^1.0.0-alpha.6",
-    "@jupyterlab/inspector": "^1.0.0-alpha.6",
     "@jupyterlab/inspector-extension": "^1.0.0-alpha.6",
     "@jupyterlab/javascript-extension": "^1.0.0-alpha.6",
     "@jupyterlab/json-extension": "^1.0.0-alpha.6",
     "@jupyterlab/launcher": "^1.0.0-alpha.6",
     "@jupyterlab/launcher-extension": "^1.0.0-alpha.6",
-    "@jupyterlab/mainmenu": "^1.0.0-alpha.6",
     "@jupyterlab/mainmenu-extension": "^1.0.0-alpha.6",
-    "@jupyterlab/markdownviewer": "^1.0.0-alpha.6",
     "@jupyterlab/markdownviewer-extension": "^1.0.0-alpha.6",
-    "@jupyterlab/mathjax2": "^1.0.0-alpha.6",
     "@jupyterlab/mathjax2-extension": "^1.0.0-alpha.6",
-    "@jupyterlab/nbconvert-css": "^0.1.0",
     "@jupyterlab/notebook": "^1.0.0-alpha.7",
     "@jupyterlab/notebook-extension": "^1.0.0-alpha.6",
-    "@jupyterlab/observables": "^2.2.0-alpha.6",
-    "@jupyterlab/outputarea": "^1.0.0-alpha.6",
     "@jupyterlab/pdf-extension": "^1.0.0-alpha.6",
     "@jupyterlab/rendermime": "^1.0.0-alpha.6",
     "@jupyterlab/rendermime-extension": "^1.0.0-alpha.6",
     "@jupyterlab/rendermime-interfaces": "^1.3.0-alpha.6",
-    "@jupyterlab/running": "^1.0.0-alpha.6",
     "@jupyterlab/running-extension": "^1.0.0-alpha.6",
     "@jupyterlab/services": "^4.0.0-alpha.6",
-    "@jupyterlab/settingeditor": "^1.0.0-alpha.6",
     "@jupyterlab/settingeditor-extension": "^1.0.0-alpha.6",
     "@jupyterlab/shortcuts-extension": "^1.0.0-alpha.6",
-    "@jupyterlab/statusbar": "^1.0.0-alpha.6",
     "@jupyterlab/statusbar-extension": "^1.0.0-alpha.6",
     "@jupyterlab/tabmanager-extension": "^1.0.0-alpha.6",
     "@jupyterlab/terminal": "^1.0.0-alpha.6",
@@ -81,8 +62,6 @@
     "@jupyterlab/theme-light-extension": "^1.0.0-alpha.7",
     "@jupyterlab/tooltip": "^1.0.0-alpha.6",
     "@jupyterlab/tooltip-extension": "^1.0.0-alpha.6",
-    "@jupyterlab/ui-components": "^1.0.0-alpha.6",
-    "@jupyterlab/vdom": "^1.0.0-alpha.6",
     "@jupyterlab/vdom-extension": "^1.0.0-alpha.6",
     "@jupyterlab/vega5-extension": "^1.0.0-alpha.6",
     "@phosphor/algorithm": "^1.1.2",
@@ -91,12 +70,9 @@
     "@phosphor/coreutils": "^1.3.0",
     "@phosphor/datagrid": "^0.1.6",
     "@phosphor/disposable": "^1.1.2",
-    "@phosphor/domutils": "^1.1.2",
-    "@phosphor/dragdrop": "^1.3.0",
     "@phosphor/messaging": "^1.2.2",
     "@phosphor/properties": "^1.1.2",
     "@phosphor/signaling": "^1.2.2",
-    "@phosphor/virtualdom": "^1.1.2",
     "@phosphor/widgets": "^1.6.0",
     "ajv": "^6.5.5",
     "codemirror": "~5.46.0",
@@ -107,11 +83,7 @@
     "path-posix": "~1.0.0",
     "react": "~16.8.4",
     "react-dom": "~16.8.4",
-    "react-paginate": "^5.2.3",
-    "sanitize-html": "~1.18.2",
-    "semver": "^5.5.0",
-    "url-parse": "~1.4.3",
-    "xterm": "~3.10.1"
+    "url-parse": "~1.4.3"
   },
   "devDependencies": {
     "@jupyterlab/buildutils": "^1.0.0-alpha.6",
@@ -240,75 +212,40 @@
     "linkedPackages": {
       "@jupyterlab/application": "../packages/application",
       "@jupyterlab/application-extension": "../packages/application-extension",
-      "@jupyterlab/apputils": "../packages/apputils",
       "@jupyterlab/apputils-extension": "../packages/apputils-extension",
-      "@jupyterlab/attachments": "../packages/attachments",
-      "@jupyterlab/cells": "../packages/cells",
-      "@jupyterlab/codeeditor": "../packages/codeeditor",
-      "@jupyterlab/codemirror": "../packages/codemirror",
       "@jupyterlab/codemirror-extension": "../packages/codemirror-extension",
-      "@jupyterlab/completer": "../packages/completer",
       "@jupyterlab/completer-extension": "../packages/completer-extension",
-      "@jupyterlab/console": "../packages/console",
       "@jupyterlab/console-extension": "../packages/console-extension",
       "@jupyterlab/coreutils": "../packages/coreutils",
-      "@jupyterlab/csvviewer": "../packages/csvviewer",
       "@jupyterlab/csvviewer-extension": "../packages/csvviewer-extension",
-      "@jupyterlab/docmanager": "../packages/docmanager",
       "@jupyterlab/docmanager-extension": "../packages/docmanager-extension",
-      "@jupyterlab/docregistry": "../packages/docregistry",
-      "@jupyterlab/documentsearch": "../packages/documentsearch",
       "@jupyterlab/documentsearch-extension": "../packages/documentsearch-extension",
-      "@jupyterlab/extensionmanager": "../packages/extensionmanager",
       "@jupyterlab/extensionmanager-extension": "../packages/extensionmanager-extension",
       "@jupyterlab/faq-extension": "../packages/faq-extension",
-      "@jupyterlab/filebrowser": "../packages/filebrowser",
       "@jupyterlab/filebrowser-extension": "../packages/filebrowser-extension",
-      "@jupyterlab/fileeditor": "../packages/fileeditor",
       "@jupyterlab/fileeditor-extension": "../packages/fileeditor-extension",
       "@jupyterlab/help-extension": "../packages/help-extension",
-      "@jupyterlab/htmlviewer": "../packages/htmlviewer",
       "@jupyterlab/htmlviewer-extension": "../packages/htmlviewer-extension",
-      "@jupyterlab/imageviewer": "../packages/imageviewer",
       "@jupyterlab/imageviewer-extension": "../packages/imageviewer-extension",
-      "@jupyterlab/inspector": "../packages/inspector",
       "@jupyterlab/inspector-extension": "../packages/inspector-extension",
       "@jupyterlab/javascript-extension": "../packages/javascript-extension",
       "@jupyterlab/json-extension": "../packages/json-extension",
-      "@jupyterlab/launcher": "../packages/launcher",
       "@jupyterlab/launcher-extension": "../packages/launcher-extension",
-      "@jupyterlab/mainmenu": "../packages/mainmenu",
       "@jupyterlab/mainmenu-extension": "../packages/mainmenu-extension",
-      "@jupyterlab/markdownviewer": "../packages/markdownviewer",
       "@jupyterlab/markdownviewer-extension": "../packages/markdownviewer-extension",
-      "@jupyterlab/mathjax2": "../packages/mathjax2",
       "@jupyterlab/mathjax2-extension": "../packages/mathjax2-extension",
-      "@jupyterlab/nbconvert-css": "../packages/nbconvert-css",
-      "@jupyterlab/notebook": "../packages/notebook",
       "@jupyterlab/notebook-extension": "../packages/notebook-extension",
-      "@jupyterlab/observables": "../packages/observables",
-      "@jupyterlab/outputarea": "../packages/outputarea",
       "@jupyterlab/pdf-extension": "../packages/pdf-extension",
-      "@jupyterlab/rendermime": "../packages/rendermime",
       "@jupyterlab/rendermime-extension": "../packages/rendermime-extension",
-      "@jupyterlab/rendermime-interfaces": "../packages/rendermime-interfaces",
-      "@jupyterlab/running": "../packages/running",
       "@jupyterlab/running-extension": "../packages/running-extension",
-      "@jupyterlab/services": "../packages/services",
-      "@jupyterlab/settingeditor": "../packages/settingeditor",
       "@jupyterlab/settingeditor-extension": "../packages/settingeditor-extension",
       "@jupyterlab/shortcuts-extension": "../packages/shortcuts-extension",
-      "@jupyterlab/statusbar": "../packages/statusbar",
       "@jupyterlab/statusbar-extension": "../packages/statusbar-extension",
       "@jupyterlab/tabmanager-extension": "../packages/tabmanager-extension",
-      "@jupyterlab/terminal": "../packages/terminal",
       "@jupyterlab/terminal-extension": "../packages/terminal-extension",
       "@jupyterlab/theme-dark-extension": "../packages/theme-dark-extension",
       "@jupyterlab/theme-light-extension": "../packages/theme-light-extension",
-      "@jupyterlab/tooltip": "../packages/tooltip",
       "@jupyterlab/tooltip-extension": "../packages/tooltip-extension",
-      "@jupyterlab/ui-components": "../packages/ui-components",
-      "@jupyterlab/vdom": "../packages/vdom",
       "@jupyterlab/vdom-extension": "../packages/vdom-extension",
       "@jupyterlab/vega5-extension": "../packages/vega5-extension"
     }
diff --git a/packages/application/package.json b/packages/application/package.json
index 6c2fa7ebbd17..b783e123b274 100644
--- a/packages/application/package.json
+++ b/packages/application/package.json
@@ -56,5 +56,8 @@
   },
   "publishConfig": {
     "access": "public"
+  },
+  "jupyterlab": {
+    "coreDependency": true
   }
 }
diff --git a/packages/coreutils/package.json b/packages/coreutils/package.json
index 8f7752891114..32d47f23cde8 100644
--- a/packages/coreutils/package.json
+++ b/packages/coreutils/package.json
@@ -50,5 +50,8 @@
   },
   "publishConfig": {
     "access": "public"
+  },
+  "jupyterlab": {
+    "coreDependency": true
   }
 }