diff --git a/code-actions-sample/README.md b/code-actions-sample/README.md
index 68a867aa..20c285de 100644
--- a/code-actions-sample/README.md
+++ b/code-actions-sample/README.md
@@ -4,11 +4,16 @@ This sample shows how to provide code actions in the the editor. Code actions ar
 
 The sample uses the [`CodeActionProvider`](https://code.visualstudio.com/api/references/vscode-api#CodeActionProvider) api to implement a simple set of code actions that convert `:)` to a smiley emoji in markdown files:
 
-![](example.gif)
+![Emoji code actions](example.gif)
 
+Second example of code action provider shows how to associate code actions with diagnostic (e.g. compilation) problems.
+
+![Diagnostic code actions](example_diagnostic.gif)
 
 ## VS Code API
 
 ### `vscode` module
 
 - [`languages.registerCodeActionsProvider`](https://code.visualstudio.com/api/references/vscode-api#languages.registerCodeActionsProvider)
+- [`Diagnostic.code`](https://code.visualstudio.com/api/references/vscode-api#Diagnostic)
+- [`CodeActionContext.diagnostics`](https://code.visualstudio.com/api/references/vscode-api#CodeActionContext)
diff --git a/code-actions-sample/example_diagnostic.gif b/code-actions-sample/example_diagnostic.gif
new file mode 100644
index 00000000..2d4830ad
Binary files /dev/null and b/code-actions-sample/example_diagnostic.gif differ
diff --git a/code-actions-sample/src/diagnostics.ts b/code-actions-sample/src/diagnostics.ts
new file mode 100644
index 00000000..680da884
--- /dev/null
+++ b/code-actions-sample/src/diagnostics.ts
@@ -0,0 +1,67 @@
+/*---------------------------------------------------------
+ * Copyright (C) Microsoft Corporation. All rights reserved.
+ *--------------------------------------------------------*/
+
+/** To demonstrate code actions associated with Diagnostics problems, this file provides a mock diagnostics entries. */
+
+import * as vscode from 'vscode';
+
+/** Code that is used to associate diagnostic entries with code actions. */
+export const EMOJI_MENTION = 'emoji_mention';
+
+/** String to detect in the text document. */
+const EMOJI = 'emoji';
+
+/**
+ * Analyzes the text document for problems. 
+ * This demo diagnostic problem provider finds all mentions of 'emoji'.
+ * @param doc text document to analyze
+ * @param emojiDiagnostics diagnostic collection
+ */
+export function refreshDiagnostics(doc: vscode.TextDocument, emojiDiagnostics: vscode.DiagnosticCollection): void {
+	let diagnostics: vscode.Diagnostic[] = [];
+
+	for (let lineIndex = 0; lineIndex < doc.lineCount; lineIndex++) {
+		const lineOfText = doc.lineAt(lineIndex);
+		if (lineOfText.text.includes(EMOJI)) {
+			diagnostics.push(createDiagnostic(doc, lineOfText, lineIndex));
+		}
+	}
+
+	emojiDiagnostics.set(doc.uri, diagnostics);
+}
+
+function createDiagnostic(doc: vscode.TextDocument, lineOfText: vscode.TextLine, lineIndex: number): vscode.Diagnostic {
+	// find where in the line of thet the 'emoji' is mentioned
+	let index = lineOfText.text.indexOf(EMOJI);
+
+	// create range that represents, where in the document the word is
+	let range = new vscode.Range(lineIndex, index, lineIndex, index + EMOJI.length);
+
+	let diagnostic = new vscode.Diagnostic(range, "When you say 'emoji', do you want to find out more?",
+		vscode.DiagnosticSeverity.Information);
+	diagnostic.code = EMOJI_MENTION;
+	return diagnostic;
+}
+
+export function subscribeToDocumentChanges(context: vscode.ExtensionContext, emojiDiagnostics: vscode.DiagnosticCollection): void {
+	if (vscode.window.activeTextEditor) {
+		refreshDiagnostics(vscode.window.activeTextEditor.document, emojiDiagnostics);
+	}
+	context.subscriptions.push(
+		vscode.window.onDidChangeActiveTextEditor(editor => {
+			if (editor) {
+				refreshDiagnostics(editor.document, emojiDiagnostics);
+			}
+		})
+	);
+
+	context.subscriptions.push(
+		vscode.workspace.onDidChangeTextDocument(e => refreshDiagnostics(e.document, emojiDiagnostics))
+	);
+
+	context.subscriptions.push(
+		vscode.workspace.onDidCloseTextDocument(doc => emojiDiagnostics.delete(doc.uri))
+	);
+
+}
\ No newline at end of file
diff --git a/code-actions-sample/src/extension.ts b/code-actions-sample/src/extension.ts
index 1149c3f2..2279301f 100644
--- a/code-actions-sample/src/extension.ts
+++ b/code-actions-sample/src/extension.ts
@@ -3,12 +3,37 @@
  *--------------------------------------------------------*/
 
 import * as vscode from 'vscode';
+import { subscribeToDocumentChanges, EMOJI_MENTION } from './diagnostics';
+
+const COMMAND = 'code-actions-sample.command';
+
+var emojiDiagnostics: vscode.DiagnosticCollection;
 
 export function activate(context: vscode.ExtensionContext) {
 	context.subscriptions.push(
 		vscode.languages.registerCodeActionsProvider('markdown', new Emojizer(), {
 			providedCodeActionKinds: Emojizer.providedCodeActionKinds
 		}));
+
+	emojiDiagnostics = vscode.languages.createDiagnosticCollection("emoji");
+
+	subscribeToDocumentChanges(context, emojiDiagnostics);
+
+	context.subscriptions.push(
+		vscode.languages.registerCodeActionsProvider('markdown', new Emojinfo(), {
+			providedCodeActionKinds: Emojinfo.providedCodeActionKinds
+		})
+	);
+
+	context.subscriptions.push(
+		vscode.commands.registerCommand(COMMAND, () => vscode.env.openExternal(vscode.Uri.parse('https://unicode.org/emoji/charts-12.0/full-emoji-list.html')))
+	);
+}
+
+export function deactivate(context: vscode.ExtensionContext) {
+	if (emojiDiagnostics) {
+		emojiDiagnostics.dispose();
+	}
 }
 
 /**
@@ -34,10 +59,13 @@ export class Emojizer implements vscode.CodeActionProvider {
 
 		const replaceWithSmileyHankyFix = this.createFix(document, range, '💩');
 
+		const commandAction = this.createCommand();
+
 		return [
 			replaceWithSmileyCatFix,
 			replaceWithSmileyFix,
-			replaceWithSmileyHankyFix
+			replaceWithSmileyHankyFix,
+			commandAction
 		];
 	}
 
@@ -53,5 +81,35 @@ export class Emojizer implements vscode.CodeActionProvider {
 		fix.edit.replace(document.uri, new vscode.Range(range.start, range.start.translate(0, 2)), emoji);
 		return fix;
 	}
+
+	private createCommand(): vscode.CodeAction {
+		const action = new vscode.CodeAction('Learn more...', vscode.CodeActionKind.Empty);
+		action.command = { command: COMMAND, title: 'Learn more about emojis', tooltip: 'This will open the unicode emoji page.' };
+		return action;
+	}
 }
 
+/**
+ * Provides code actions corresponding to diagnostic problems.
+ */
+export class Emojinfo implements vscode.CodeActionProvider {
+
+	public static readonly providedCodeActionKinds = [
+		vscode.CodeActionKind.QuickFix
+	];
+
+	provideCodeActions(document: vscode.TextDocument, range: vscode.Range | vscode.Selection, context: vscode.CodeActionContext, token: vscode.CancellationToken): vscode.CodeAction[] {
+		// for each diagnostic entry that has the matching `code`, create a code action command
+		return context.diagnostics
+			.filter(diagnostic => diagnostic.code === EMOJI_MENTION)
+			.map(diagnostic => this.createCommandCodeAction(diagnostic));
+	}
+
+	private createCommandCodeAction(diagnostic: vscode.Diagnostic): vscode.CodeAction {
+		const action = new vscode.CodeAction('Learn more...', vscode.CodeActionKind.QuickFix);
+		action.command = { command: COMMAND, title: 'Learn more about emojis', tooltip: 'This will open the unicode emoji page.' };
+		action.diagnostics = [diagnostic];
+		action.isPreferred = true;
+		return action;
+	}
+}
\ No newline at end of file