diff --git a/change/@microsoft-fast-element-07e66f75-3b9f-4287-b48c-3151388366f4.json b/change/@microsoft-fast-element-07e66f75-3b9f-4287-b48c-3151388366f4.json
new file mode 100644
index 00000000000..7ee72fa56da
--- /dev/null
+++ b/change/@microsoft-fast-element-07e66f75-3b9f-4287-b48c-3151388366f4.json
@@ -0,0 +1,7 @@
+{
+  "type": "minor",
+  "comment": "feat: add warn/error message infrastructure",
+  "packageName": "@microsoft/fast-element",
+  "email": "roeisenb@microsoft.com",
+  "dependentChangeType": "patch"
+}
diff --git a/packages/web-components/fast-element/docs/api-report.md b/packages/web-components/fast-element/docs/api-report.md
index 4ca7cc34f55..3150ac39d7c 100644
--- a/packages/web-components/fast-element/docs/api-report.md
+++ b/packages/web-components/fast-element/docs/api-report.md
@@ -74,8 +74,11 @@ export class AttributeDefinition implements Accessor {
     setValue(source: HTMLElement, newValue: any): void;
 }
 
+// Warning: (ae-forgotten-export) The symbol "reflectMode" needs to be exported by the entry point index.d.ts
+// Warning: (ae-forgotten-export) The symbol "booleanMode" needs to be exported by the entry point index.d.ts
+//
 // @public
-export type AttributeMode = "reflect" | "boolean" | "fromView";
+export type AttributeMode = typeof reflectMode | typeof booleanMode | "fromView";
 
 // @public
 export interface Behavior<TSource = any, TParent = any, TGrandparent = any> {
@@ -340,10 +343,13 @@ export class FASTElementDefinition<TType extends Function = Function> {
 //
 // @internal
 export interface FASTGlobal {
+    addMessages(messages: Record<number, string>): void;
+    error(code: number, ...args: any[]): Error;
     getById<T>(id: string | number): T | null;
     // (undocumented)
     getById<T>(id: string | number, initialize: () => T): T;
     readonly versions: string[];
+    warn(code: number, ...args: any[]): void;
 }
 
 // @public
diff --git a/packages/web-components/fast-element/package.json b/packages/web-components/fast-element/package.json
index aa3b0a10ee5..10d006ed3f3 100644
--- a/packages/web-components/fast-element/package.json
+++ b/packages/web-components/fast-element/package.json
@@ -1,7 +1,6 @@
 {
   "name": "@microsoft/fast-element",
   "description": "A library for constructing Web Components",
-  "sideEffects": false,
   "version": "1.10.1",
   "author": {
     "name": "Microsoft",
@@ -20,6 +19,10 @@
   "types": "dist/fast-element.d.ts",
   "type": "module",
   "unpkg": "dist/fast-element.min.js",
+  "sideEffects": [
+    "./dist/esm/debug.js",
+    "./dist/esm/polyfills.js"
+  ],
   "scripts": {
     "clean:dist": "node ../../../build/clean.js dist",
     "doc": "api-extractor run --local",
diff --git a/packages/web-components/fast-element/src/components/attributes.ts b/packages/web-components/fast-element/src/components/attributes.ts
index cb3051f44f4..09923498593 100644
--- a/packages/web-components/fast-element/src/components/attributes.ts
+++ b/packages/web-components/fast-element/src/components/attributes.ts
@@ -22,6 +22,9 @@ export interface ValueConverter {
     fromView(value: any): any;
 }
 
+const booleanMode = "boolean";
+const reflectMode = "reflect";
+
 /**
  * The mode that specifies the runtime behavior of the attribute.
  * @remarks
@@ -33,7 +36,7 @@ export interface ValueConverter {
  * changes in the DOM, but does not reflect property changes back.
  * @public
  */
-export type AttributeMode = "reflect" | "boolean" | "fromView";
+export type AttributeMode = typeof reflectMode | typeof booleanMode | "fromView";
 
 /**
  * Metadata used to configure a custom attribute's behavior.
@@ -149,7 +152,7 @@ export class AttributeDefinition implements Accessor {
         Owner: Function,
         name: string,
         attribute: string = name.toLowerCase(),
-        mode: AttributeMode = "reflect",
+        mode: AttributeMode = reflectMode,
         converter?: ValueConverter
     ) {
         this.Owner = Owner;
@@ -161,7 +164,7 @@ export class AttributeDefinition implements Accessor {
         this.callbackName = `${name}Changed`;
         this.hasCallback = this.callbackName in Owner.prototype;
 
-        if (mode === "boolean" && converter === void 0) {
+        if (mode === booleanMode && converter === void 0) {
             this.converter = booleanConverter;
         }
     }
@@ -226,7 +229,7 @@ export class AttributeDefinition implements Accessor {
             const latestValue = element[this.fieldName];
 
             switch (mode) {
-                case "reflect":
+                case reflectMode:
                     const converter = this.converter;
                     DOM.setAttribute(
                         element,
@@ -234,7 +237,7 @@ export class AttributeDefinition implements Accessor {
                         converter !== void 0 ? converter.toView(latestValue) : latestValue
                     );
                     break;
-                case "boolean":
+                case booleanMode:
                     DOM.setBooleanAttribute(element, this.attribute, latestValue);
                     break;
             }
diff --git a/packages/web-components/fast-element/src/components/controller.ts b/packages/web-components/fast-element/src/components/controller.ts
index ccdc5b29a30..7b6df838c59 100644
--- a/packages/web-components/fast-element/src/components/controller.ts
+++ b/packages/web-components/fast-element/src/components/controller.ts
@@ -1,7 +1,8 @@
-import type { Mutable, StyleTarget } from "../interfaces.js";
+import { Message, Mutable, StyleTarget } from "../interfaces.js";
 import type { Behavior } from "../observation/behavior.js";
 import { PropertyChangeNotifier } from "../observation/notifier.js";
 import { defaultExecutionContext, Observable } from "../observation/observable.js";
+import { FAST } from "../platform.js";
 import type { ElementStyles } from "../styles/element-styles.js";
 import type { ElementViewTemplate } from "../templating/template.js";
 import type { ElementView } from "../templating/view.js";
@@ -18,6 +19,8 @@ function getShadowRoot(element: HTMLElement): ShadowRoot | null {
     return element.shadowRoot ?? shadowRoots.get(element) ?? null;
 }
 
+const isConnectedPropertyName = "isConnected";
+
 /**
  * Controls the lifecycle and rendering of a `FASTElement`.
  * @public
@@ -64,13 +67,13 @@ export class Controller extends PropertyChangeNotifier {
      * connected to the document.
      */
     public get isConnected(): boolean {
-        Observable.track(this, "isConnected");
+        Observable.track(this, isConnectedPropertyName);
         return this._isConnected;
     }
 
     private setIsConnected(value: boolean): void {
         this._isConnected = value;
-        Observable.notify(this, "isConnected");
+        Observable.notify(this, isConnectedPropertyName);
     }
 
     /**
@@ -474,7 +477,7 @@ export class Controller extends PropertyChangeNotifier {
         const definition = FASTElementDefinition.forType(element.constructor);
 
         if (definition === void 0) {
-            throw new Error("Missing FASTElement definition.");
+            throw FAST.error(Message.missingElementDefinition);
         }
 
         return ((element as any).$fastController = new Controller(element, definition));
diff --git a/packages/web-components/fast-element/src/debug.spec.ts b/packages/web-components/fast-element/src/debug.spec.ts
new file mode 100644
index 00000000000..b907f3cfa84
--- /dev/null
+++ b/packages/web-components/fast-element/src/debug.spec.ts
@@ -0,0 +1,20 @@
+import { expect } from "chai";
+import "./debug.js";
+import { FASTGlobal, Message } from "./interfaces";
+
+declare const FAST: FASTGlobal;
+
+describe("The debug module", () => {
+    context("when sending errors", () => {
+        it("expect known error message from known error code", () => {
+            const error = FAST.error(Message.bindingInnerHTMLRequiresTrustedTypes);
+            expect(error.message.length).greaterThan(0);
+            expect(error.message).not.equal("Unknown Error");
+        });
+
+        it("expect unknown error message from unknown error code", () => {
+            const error = FAST.error(10);
+            expect(error.message).equal("Unknown Error");
+        });
+    });
+});
diff --git a/packages/web-components/fast-element/src/debug.ts b/packages/web-components/fast-element/src/debug.ts
new file mode 100644
index 00000000000..30ed0a78860
--- /dev/null
+++ b/packages/web-components/fast-element/src/debug.ts
@@ -0,0 +1,31 @@
+import type { FASTGlobal } from "./interfaces.js";
+
+if (globalThis.FAST === void 0) {
+    Reflect.defineProperty(globalThis, "FAST", {
+        value: Object.create(null),
+        configurable: false,
+        enumerable: false,
+        writable: false,
+    });
+}
+
+const FAST: FASTGlobal = globalThis.FAST;
+
+const debugMessages = {
+    [1101 /* needsArrayObservation */]: "Must call enableArrayObservation before observing arrays.",
+    [1201 /* onlySetHTMLPolicyOnce */]: "The HTML policy can only be set once.",
+    [1202 /* bindingInnerHTMLRequiresTrustedTypes */]: "To bind innerHTML, you must use a TrustedTypesPolicy.",
+    [1401 /* missingElementDefinition */]: "Missing FASTElement definition.",
+};
+
+Object.assign(FAST, {
+    addMessages(messages: Record<number, string>) {
+        Object.assign(debugMessages, messages);
+    },
+    warn(code: number, ...args: any[]) {
+        console.warn(debugMessages[code] ?? "Unknown Warning");
+    },
+    error(code: number, ...args: any[]) {
+        return new Error(debugMessages[code] ?? "Unknown Error");
+    },
+});
diff --git a/packages/web-components/fast-element/src/interfaces.ts b/packages/web-components/fast-element/src/interfaces.ts
index 59da7930884..7f7179b6f8f 100644
--- a/packages/web-components/fast-element/src/interfaces.ts
+++ b/packages/web-components/fast-element/src/interfaces.ts
@@ -63,6 +63,26 @@ export interface FASTGlobal {
      */
     getById<T>(id: string | number): T | null;
     getById<T>(id: string | number, initialize: () => T): T;
+
+    /**
+     * Sends a warning to the developer.
+     * @param code - The warning code to send.
+     * @param args - Args relevant for the warning.
+     */
+    warn(code: number, ...args: any[]): void;
+
+    /**
+     * Creates an error.
+     * @param code - The error code to send.
+     * @param args - Args relevant for the error.
+     */
+    error(code: number, ...args: any[]): Error;
+
+    /**
+     * Adds debug messages for errors and warnings.
+     * @param messages - The message dictionary to add.
+     */
+    addMessages(messages: Record<number, string>): void;
 }
 
 /**
@@ -75,6 +95,7 @@ export const enum KernelServiceId {
     contextEvent = 3,
     elementRegistry = 4,
     styleSheetStrategy = 5,
+    developerChannel = 6,
 }
 
 /**
@@ -125,6 +146,22 @@ export interface StyleStrategy {
     removeStylesFrom(target: StyleTarget): void;
 }
 
+/**
+ * Warning and error messages.
+ * @internal
+ */
+export const enum Message {
+    // 1000 - 1100 Kernel
+    // 1101 - 1200 Observation
+    needsArrayObservation = 1101,
+    // 1201 - 1300 Templating
+    onlySetHTMLPolicyOnce = 1201,
+    bindingInnerHTMLRequiresTrustedTypes = 1202,
+    // 1301 - 1400 Styles
+    // 1401 - 1500 Components
+    missingElementDefinition = 1401,
+}
+
 /**
  * @internal
  */
diff --git a/packages/web-components/fast-element/src/observation/observable.ts b/packages/web-components/fast-element/src/observation/observable.ts
index e07c0571839..0ae6883287a 100644
--- a/packages/web-components/fast-element/src/observation/observable.ts
+++ b/packages/web-components/fast-element/src/observation/observable.ts
@@ -1,5 +1,5 @@
 import { DOM } from "../dom.js";
-import { isFunction, isString, KernelServiceId } from "../interfaces.js";
+import { isFunction, isString, KernelServiceId, Message } from "../interfaces.js";
 import { FAST } from "../platform.js";
 import { PropertyChangeNotifier, SubscriberSet } from "./notifier.js";
 import type { Notifier, Subscriber } from "./notifier.js";
@@ -97,7 +97,7 @@ export const Observable = FAST.getById(KernelServiceId.observable, () => {
     const accessorLookup = new WeakMap<any, Accessor[]>();
     let watcher: BindingObserverImplementation | undefined = void 0;
     let createArrayObserver = (array: any[]): Notifier => {
-        throw new Error("Must call enableArrayObservation before observing arrays.");
+        throw FAST.error(Message.needsArrayObservation);
     };
 
     function getNotifier(source: any): Notifier {
diff --git a/packages/web-components/fast-element/src/platform.ts b/packages/web-components/fast-element/src/platform.ts
index 38a0c5d06a2..f334c47c9b8 100644
--- a/packages/web-components/fast-element/src/platform.ts
+++ b/packages/web-components/fast-element/src/platform.ts
@@ -1,6 +1,6 @@
 import type { FASTGlobal } from "./interfaces.js";
 
-// ensure FAST global - duplicated in polyfills.ts
+// ensure FAST global - duplicated in polyfills.ts and debug.ts
 const propConfig = {
     configurable: false,
     enumerable: false,
@@ -37,6 +37,16 @@ if (FAST.getById === void 0) {
     });
 }
 
+if (FAST.error === void 0) {
+    Object.assign(FAST, {
+        warn() {},
+        error(code: number) {
+            return new Error(`Code ${code}`);
+        },
+        addMessages() {},
+    });
+}
+
 /**
  * A readonly, empty array.
  * @remarks
diff --git a/packages/web-components/fast-element/src/templating/binding.ts b/packages/web-components/fast-element/src/templating/binding.ts
index 8194b18ba00..ef067c9c302 100644
--- a/packages/web-components/fast-element/src/templating/binding.ts
+++ b/packages/web-components/fast-element/src/templating/binding.ts
@@ -1,11 +1,12 @@
 import { DOM } from "../dom.js";
-import { isString, Mutable } from "../interfaces.js";
+import { isString, Message, Mutable } from "../interfaces.js";
 import {
     Binding,
     BindingObserver,
     ExecutionContext,
     Observable,
 } from "../observation/observable.js";
+import { FAST } from "../platform.js";
 import {
     Aspect,
     AspectedHTMLDirective,
@@ -502,7 +503,7 @@ const createInnerHTMLBinding = globalThis.TrustedHTML
               return value;
           }
 
-          throw new Error("To bind innerHTML, you must use a TrustedTypesPolicy.");
+          throw FAST.error(Message.bindingInnerHTMLRequiresTrustedTypes);
       }
     : (binding: Binding) => binding;
 
diff --git a/packages/web-components/fast-element/src/templating/compiler.ts b/packages/web-components/fast-element/src/templating/compiler.ts
index baed861fd83..232d5ecfafd 100644
--- a/packages/web-components/fast-element/src/templating/compiler.ts
+++ b/packages/web-components/fast-element/src/templating/compiler.ts
@@ -1,5 +1,6 @@
-import { isString, TrustedTypesPolicy } from "../interfaces.js";
+import { isString, Message, TrustedTypesPolicy } from "../interfaces.js";
 import type { ExecutionContext } from "../observation/observable.js";
+import { FAST } from "../platform.js";
 import { Parser } from "./markup.js";
 import { bind, oneTime } from "./binding.js";
 import type {
@@ -286,7 +287,7 @@ export const Compiler = {
      */
     setHTMLPolicy(policy: TrustedTypesPolicy) {
         if (htmlPolicy !== fastHTMLPolicy) {
-            throw new Error("The HTML policy can only be set once.");
+            throw FAST.error(Message.onlySetHTMLPolicyOnce);
         }
 
         htmlPolicy = policy;
diff --git a/packages/web-components/fast-element/src/templating/slotted.ts b/packages/web-components/fast-element/src/templating/slotted.ts
index a231041da16..9c2a697d749 100644
--- a/packages/web-components/fast-element/src/templating/slotted.ts
+++ b/packages/web-components/fast-element/src/templating/slotted.ts
@@ -2,6 +2,8 @@ import { isString } from "../interfaces.js";
 import { NodeBehaviorOptions, NodeObservationDirective } from "./node-observation.js";
 import type { CaptureType } from "./template.js";
 
+const slotEvent = "slotchange";
+
 /**
  * The options used to configure slotted node observation.
  * @public
@@ -20,7 +22,7 @@ export class SlottedDirective extends NodeObservationDirective<SlottedDirectiveO
      * @param target - The target to observe.
      */
     observe(target: EventSource): void {
-        target.addEventListener("slotchange", this);
+        target.addEventListener(slotEvent, this);
     }
 
     /**
@@ -28,7 +30,7 @@ export class SlottedDirective extends NodeObservationDirective<SlottedDirectiveO
      * @param target - The target to unobserve.
      */
     disconnect(target: EventSource): void {
-        target.removeEventListener("slotchange", this);
+        target.removeEventListener(slotEvent, this);
     }
 
     /**