diff --git a/src/extension.ts b/src/extension.ts
index ed0ad28..00347cf 100644
--- a/src/extension.ts
+++ b/src/extension.ts
@@ -55,6 +55,22 @@ function showFunctionDetails(
   detailsChannel.show(true /* preserveFocus */);
 }
 
+/**
+ * Validates the current configuration and, if the thresholds are misconfigured
+ * (e.g. warningThreshold >= errorThreshold), surfaces a warning to the user so
+ * the issue isn't silently ignored.
+ *
+ * Exported for unit-testing purposes.
+ */
+export function checkConfigurationValidity(): void {
+  const { valid, warnings } = ConfigurationManager.validateConfiguration();
+  if (!valid) {
+    vscode.window.showWarningMessage(
+      `Code Metrics: invalid configuration detected. ${warnings.join(" ")}`
+    );
+  }
+}
+
 // This method is called when your extension is activated
 // Your extension is activated the very first time the command is executed
 export function activate(context: vscode.ExtensionContext) {
@@ -69,7 +85,17 @@ export function activate(context: vscode.ExtensionContext) {
   // Register providers
   const codeLensDisposable = registerCodeLensProvider();
 
-  context.subscriptions.push(showFunctionDetailsCommand, codeLensDisposable);
+  // Warn the user up front, and again whenever settings change, if thresholds are invalid.
+  checkConfigurationValidity();
+  const configValidityWatcher = ConfigurationManager.onConfigurationChanged(() => {
+    checkConfigurationValidity();
+  });
+
+  context.subscriptions.push(
+    showFunctionDetailsCommand,
+    codeLensDisposable,
+    configValidityWatcher
+  );
 }
 
 // This method is called when your extension is deactivated
diff --git a/src/test/extension.test.ts b/src/test/extension.test.ts
index 4aee666..0f8d959 100644
--- a/src/test/extension.test.ts
+++ b/src/test/extension.test.ts
@@ -147,4 +147,89 @@ suite("Extension Activation Tests", () => {
       extensionModule.deactivate();
     }, "deactivate() should not throw");
   });
+
+  suite("checkConfigurationValidity", () => {
+    // Stub type to capture showWarningMessage calls
+    type ShowWarningStub = (message: string, ...items: string[]) => Thenable<string | undefined>;
+
+    let warningMessages: string[];
+    let originalShowWarningMessage: typeof vscode.window.showWarningMessage;
+
+    setup(() => {
+      warningMessages = [];
+      originalShowWarningMessage = vscode.window.showWarningMessage;
+      (vscode.window as any).showWarningMessage = ((message: string) => {
+        warningMessages.push(message);
+        return Promise.resolve(undefined);
+      }) as ShowWarningStub;
+    });
+
+    teardown(async () => {
+      (vscode.window as any).showWarningMessage = originalShowWarningMessage;
+      const vsConfig = vscode.workspace.getConfiguration("codeMetrics");
+      await vsConfig.update("warningThreshold", undefined, vscode.ConfigurationTarget.Global);
+      await vsConfig.update("errorThreshold", undefined, vscode.ConfigurationTarget.Global);
+    });
+
+    test("should not show a warning when thresholds are valid", () => {
+      // Default configuration has valid thresholds (warningThreshold < errorThreshold)
+      extensionModule.checkConfigurationValidity();
+
+      assert.strictEqual(
+        warningMessages.length,
+        0,
+        "No warning should be shown for valid configuration"
+      );
+    });
+
+    test("should show a warning when warningThreshold equals errorThreshold", async () => {
+      const vsConfig = vscode.workspace.getConfiguration("codeMetrics");
+      await vsConfig.update("warningThreshold", 10, vscode.ConfigurationTarget.Global);
+      await vsConfig.update("errorThreshold", 10, vscode.ConfigurationTarget.Global);
+
+      // Reset captured messages so that onConfigurationChanged calls from the
+      // config updates above don't pollute the assertion.
+      warningMessages = [];
+      extensionModule.checkConfigurationValidity();
+
+      assert.strictEqual(
+        warningMessages.length,
+        1,
+        "Exactly one warning should be shown"
+      );
+      assert.ok(
+        warningMessages[0].includes("Code Metrics"),
+        "Warning message should be prefixed with 'Code Metrics'"
+      );
+      assert.ok(
+        warningMessages[0].includes("invalid configuration"),
+        "Warning message should mention invalid configuration"
+      );
+    });
+
+    test("should show a warning when warningThreshold exceeds errorThreshold", async () => {
+      const vsConfig = vscode.workspace.getConfiguration("codeMetrics");
+      await vsConfig.update("warningThreshold", 20, vscode.ConfigurationTarget.Global);
+      await vsConfig.update("errorThreshold", 10, vscode.ConfigurationTarget.Global);
+
+      // Reset captured messages so that onConfigurationChanged calls from the
+      // config updates above don't pollute the assertion.
+      warningMessages = [];
+      extensionModule.checkConfigurationValidity();
+
+      assert.strictEqual(
+        warningMessages.length,
+        1,
+        "Exactly one warning should be shown"
+      );
+      assert.ok(
+        warningMessages[0].includes("Warning threshold (20)"),
+        "Warning message should include the invalid warningThreshold value"
+      );
+      assert.ok(
+        warningMessages[0].includes("error threshold (10)"),
+        "Warning message should include the errorThreshold value"
+      );
+    });
+  });
 });