diff --git a/packages/optimizely-sdk/lib/index.d.ts b/packages/optimizely-sdk/lib/index.d.ts
new file mode 100644
index 000000000..5fb8a55ac
--- /dev/null
+++ b/packages/optimizely-sdk/lib/index.d.ts
@@ -0,0 +1,181 @@
+/**
+ * Copyright 2018, Optimizely
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+declare module '@optimizely/optimizely-sdk' {
+    import enums = require('@optimizely/optimizely-sdk/lib/utils/enums');
+  
+    export function createInstance(config: Config): Client;
+  
+    // The options object given to Optimizely.createInstance.
+    export interface Config {
+        datafile: object;
+        errorHandler?: object;
+        eventDispatcher?: object;
+        logger?: object;
+        logLevel?: enums.LOG_LEVEL.DEBUG | enums.LOG_LEVEL.ERROR | enums.LOG_LEVEL.INFO | enums.LOG_LEVEL.NOTSET | enums.LOG_LEVEL.WARNING;
+        skipJSONValidation?: boolean;
+        jsonSchemaValidator?: object;
+        userProfileService?: UserProfileService | null;
+    }
+  
+    export interface Client {
+        notificationCenter: NotificationCenter;
+        activate(experimentKey: string, userId: string, attributes?: UserAttributes): string | null;
+        track(eventKey: string, userId: string, attributes?: UserAttributes, eventTags?: EventTags): void;
+        getVariation(experimentKey: string, userId: string, attributes?: UserAttributes): string | null;
+        setForcedVariation(experimentKey: string, userId: string, variationKey: string | null): boolean;
+        getForcedVariation(experimentKey: string, userId: string): string | null;
+        isFeatureEnabled(featureKey: string, userId: string, attributes?: UserAttributes): boolean;
+        getEnabledFeatures(userId: string, attributes?: UserAttributes): string[];
+        getFeatureVariableBoolean(featureKey: string, variableKey: string, userId: string, attributes?: UserAttributes): boolean | null;
+        getFeatureVariableDouble(featureKey: string, variableKey: string, userId: string, attributes?: UserAttributes): number | null;
+        getFeatureVariableInteger(featureKey: string, variableKey: string, userId: string, attributes?: UserAttributes): number | null;
+        getFeatureVariableString(featureKey: string, variableKey: string, userId: string, attributes?: UserAttributes): string | null;
+    }
+  
+    // An event to be submitted to Optimizely, enabling tracking the reach and impact of
+    // tests and feature rollouts.
+    export interface Event {
+        // URL to which to send the HTTP request.
+        url: string,
+        // HTTP method with which to send the event.
+        httpVerb: 'POST',
+        // Value to send in the request body, JSON-serialized.
+        params: any,
+    }
+  
+    export interface EventDispatcher {
+        /**
+         * @param event
+         *        Event being submitted for eventual dispatch.
+         * @param callback
+         *        After the event has at least been queued for dispatch, call this function to return
+         *        control back to the Client.
+         */
+        dispatchEvent: (event: Event, callback: () => void) => void,
+    }
+  
+    export interface UserProfileService {
+        lookup: (userId: string) => UserProfile,
+        save: (profile: UserProfile) => void,
+    }
+  
+    // NotificationCenter-related types
+    export interface NotificationCenter {
+        addNotificationListener<T extends ListenerPayload>(notificationType: string, callback: NotificationListener<T>): number;
+        removeNotificationListener(listenerId: number): boolean;
+        clearAllNotificationListeners(): void;
+        clearNotificationListeners(notificationType: enums.NOTIFICATION_TYPES): void;
+    }
+  
+    export type NotificationListener<T extends ListenerPayload> = (notificationData: T) => void;
+  
+    export interface ListenerPayload {
+        userId: string;
+        attributes: UserAttributes;
+    }
+  
+    export interface ActivateListenerPayload extends ListenerPayload {
+        experiment: Experiment;
+        variation: Variation;
+        logEvent: Event;
+    }
+  
+    export type UserAttributes = {
+        [name: string]: string
+    };
+  
+    export type EventTags = {
+        [key: string]: string | number | boolean,
+    };
+  
+    export interface TrackListenerPayload extends ListenerPayload {
+        eventKey: string;
+        eventTags: EventTags;
+        logEvent: Event;
+    }
+  
+    interface Experiment {
+        id: string,
+        key: string,
+        status: string,
+        layerId: string,
+        variations: Variation[],
+        trafficAllocation: Array<{
+            entityId: string,
+            endOfRange: number,
+        }>,
+        audienceIds: string[],
+        forcedVariations: object,
+    }
+  
+    interface Variation {
+        id: string,
+        key: string,
+    }
+  
+    export interface Logger {
+        log: (logLevel: enums.LOG_LEVEL, message: string) => void,
+    }
+  
+    // Information about past bucketing decisions for a user.
+    export interface UserProfile {
+        user_id: string,
+        experiment_bucket_map: {
+            [experiment_id: string]: {
+                variation_id: string,
+            },
+        },
+    }
+  }
+  
+  declare module '@optimizely/optimizely-sdk/lib/utils/enums'{
+    export enum LOG_LEVEL{
+        NOTSET = 0,
+        DEBUG = 1,
+        INFO = 2,
+        WARNING =  3,
+        ERROR = 4,
+    }
+    export enum NOTIFICATION_TYPES { 
+        ACTIVATE = 'ACTIVATE:experiment, user_id, attributes, variation, events',
+        TRACK = 'TRACK:event_key, user_id, attributes, event_tags, event',
+    }
+  }
+  
+  declare module '@optimizely/optimizely-sdk/lib/plugins/event_dispatcher/index.node.js' {
+  
+  }
+  
+  declare module '@optimizely/optimizely-sdk/lib/utils/json_schema_validator' {
+  
+  }
+  
+  declare module '@optimizely/optimizely-sdk/lib/plugins/error_handler' {
+  }
+  
+  declare module '@optimizely/optimizely-sdk/lib/plugins/logger' {
+    import * as Optimizely from '@optimizely/optimizely-sdk';
+    import * as enums from '@optimizely/optimizely-sdk/lib/utils/enums';
+  
+    export interface Config {
+        logLevel?: enums.LOG_LEVEL,
+        logToConsole?: boolean,
+        prefix?: string,
+    }
+    export function createLogger(config: Config): Optimizely.Logger;
+    export function createNoOpLogger(): Optimizely.Logger;
+  }
\ No newline at end of file
diff --git a/packages/optimizely-sdk/package.json b/packages/optimizely-sdk/package.json
index 8b48dc9e5..d8782fe0a 100644
--- a/packages/optimizely-sdk/package.json
+++ b/packages/optimizely-sdk/package.json
@@ -4,6 +4,7 @@
   "description": "JavaScript SDK for Optimizely X Full Stack",
   "main": "lib/index.node.js",
   "browser": "lib/index.browser.js",
+  "typings": "lib/index.d.ts",
   "scripts": {
     "test": "mocha ./lib/*.tests.js ./lib/**/*.tests.js ./lib/**/**/*tests.js --recursive",
     "test-xbrowser": "karma start karma.bs.conf.js --single-run",