diff --git a/ts/session/messages/outgoing/content/sync/ContactSyncMessage.ts b/ts/session/messages/outgoing/content/sync/ContactSyncMessage.ts
new file mode 100644
index 000000000..2c9cdd3a0
--- /dev/null
+++ b/ts/session/messages/outgoing/content/sync/ContactSyncMessage.ts
@@ -0,0 +1,31 @@
+import { SignalService } from '../../../../../protobuf';
+import { MessageParams } from '../../Message';
+import { SyncMessage } from '../';
+import { PubKey } from '../../../../types';
+import { DataMessage } from '../data';
+
+
+interface ContactSyncMessageParams extends MessageParams {
+  // Send to our devices
+  contacts: Array<PubKey>;
+  dataMessage?: DataMessage;
+}
+
+export class ContactSyncMessage extends SyncMessage {
+  private readonly contacts: Array<PubKey>;
+  private readonly dataMessage?: DataMessage;
+
+  constructor(params: ContactSyncMessageParams) {
+    super(params);
+
+    // Stubbed for now
+    this.contacts = params.contacts;
+    this.dataMessage = params.dataMessage;
+
+    this.syncProto();
+  }
+
+  protected syncProto(): SignalService.SyncMessage {
+    return new SignalService.SyncMessage();
+  }
+}
diff --git a/ts/session/messages/outgoing/content/sync/index.ts b/ts/session/messages/outgoing/content/sync/index.ts
index 6da779ff9..d17d62a83 100644
--- a/ts/session/messages/outgoing/content/sync/index.ts
+++ b/ts/session/messages/outgoing/content/sync/index.ts
@@ -1,3 +1,4 @@
-import * as SyncMessage from './SyncMessage';
+import { SyncMessage } from './SyncMessage';
+import { ContactSyncMessage } from './ContactSyncMessage';
 
-export { SyncMessage };
+export { ContactSyncMessage, SyncMessage };
diff --git a/ts/session/protocols/SessionProtocol.ts b/ts/session/protocols/SessionProtocol.ts
index 79847da82..da0f95129 100644
--- a/ts/session/protocols/SessionProtocol.ts
+++ b/ts/session/protocols/SessionProtocol.ts
@@ -3,7 +3,7 @@ import { SessionRequestMessage } from '../messages/outgoing';
 import { createOrUpdateItem, getItemById } from '../../../js/modules/data';
 import { libloki, libsignal, textsecure } from '../../window';
 import { MessageSender } from '../sending';
-import * as MessageUtils from '../utils';
+import { MessageUtils } from '../utils';
 import { PubKey } from '../types';
 
 interface StringToNumberMap {
diff --git a/ts/session/sending/MessageQueue.ts b/ts/session/sending/MessageQueue.ts
index 7077a2921..7b029a933 100644
--- a/ts/session/sending/MessageQueue.ts
+++ b/ts/session/sending/MessageQueue.ts
@@ -1,54 +1,167 @@
+import * as _ from 'lodash';
+import * as Data from '../../../js/modules/data';
+import { ConversationController } from '../../window';
+
 import { EventEmitter } from 'events';
 import {
   MessageQueueInterface,
   MessageQueueInterfaceEvents,
 } from './MessageQueueInterface';
-import { ContentMessage, OpenGroupMessage } from '../messages/outgoing';
+import {
+  ClosedGroupMessage,
+  ContentMessage,
+  OpenGroupMessage,
+  SessionRequestMessage,
+} from '../messages/outgoing';
 import { PendingMessageCache } from './PendingMessageCache';
-import { JobQueue, TypedEventEmitter } from '../utils';
+import {
+  JobQueue,
+  SyncMessageUtils,
+  TypedEventEmitter,
+} from '../utils';
+import { PubKey } from '../types';
+import { MessageSender } from '.';
+import { SessionProtocol } from '../protocols';
 
 export class MessageQueue implements MessageQueueInterface {
   public readonly events: TypedEventEmitter<MessageQueueInterfaceEvents>;
-  private readonly jobQueues: Map<string, JobQueue> = new Map();
-  private readonly cache: PendingMessageCache;
+  private readonly jobQueues: Map<PubKey, JobQueue> = new Map();
+  private readonly pendingMessageCache: PendingMessageCache;
 
   constructor() {
     this.events = new EventEmitter();
-    this.cache = new PendingMessageCache();
-    this.processAllPending();
+    this.pendingMessageCache = new PendingMessageCache();
+    void this.processAllPending();
   }
 
-  public sendUsingMultiDevice(user: string, message: ContentMessage) {
-    throw new Error('Method not implemented.');
+  public async sendUsingMultiDevice(user: PubKey, message: ContentMessage) {
+    const userLinked = await Data.getPairedDevicesFor(user.key);
+    const userDevices = userLinked.map(d => new PubKey(d));
+
+    await this.sendMessageToDevices(userDevices, message);
   }
-  public send(device: string, message: ContentMessage) {
-    throw new Error('Method not implemented.');
+
+  public async send(device: PubKey, message: ContentMessage) {
+    await this.sendMessageToDevices([device], message);
   }
-  public sendToGroup(message: ContentMessage | OpenGroupMessage) {
-    throw new Error('Method not implemented.');
+
+  public async sendMessageToDevices(
+    devices: Array<PubKey>,
+    message: ContentMessage
+  ) {
+    let currentDevices = [...devices];
+
+    // Sync to our devices if syncable
+    if (SyncMessageUtils.canSync(message)) {
+
+      const ourDevices = await SyncMessageUtils.getOurPairedDevices();
+      await this.sendSyncMessage(message, ourDevices);
+
+      // Remove our devices from currentDevices
+      const ourDeviceContacts = ourDevices.map(device => ConversationController.get(device.key));
+      currentDevices = _.xor(currentDevices, ourDeviceContacts);
+    }
+
+    const promises = currentDevices.map(async device => {
+      await this.queue(device, message);
+    });
+
+    return Promise.all(promises);
   }
-  public sendSyncMessage(message: ContentMessage) {
-    throw new Error('Method not implemented.');
+
+  public async sendToGroup(message: OpenGroupMessage | ContentMessage): Promise<boolean> {
+    if (
+      !(message instanceof OpenGroupMessage) &&
+      !(message instanceof ClosedGroupMessage)
+    ) {
+      return false;
+    }
+
+    // Closed groups
+    if (message instanceof ClosedGroupMessage) {
+      // Get devices in closed group
+      const conversation = ConversationController.get(message.groupId);
+      const recipientsModels = conversation.contactCollection.models;
+      const recipients: Array<PubKey> = recipientsModels.map(
+        (recipient: any) => new PubKey(recipient.id)
+      );
+
+      await this.sendMessageToDevices(recipients, message);
+
+      return true;
+    }
+
+    // Open groups
+    if (message instanceof OpenGroupMessage) {
+      // No queue needed for Open Groups; send directly
+      await MessageSender.sendToOpenGroup(message);
+
+      return true;
+    }
+
+    return false;
   }
 
-  public processPending(device: string) {
-    // TODO: implement
+  public async sendSyncMessage(
+    message: ContentMessage,
+    sendTo: Array<PubKey>
+  ) {
+    // Sync with our devices
+    const promises = sendTo.map(async device => {
+      const syncMessage = await SyncMessageUtils.from(message, device);
+
+      return this.queue(device, syncMessage);
+    });
+
+    return Promise.all(promises);
   }
 
-  private processAllPending() {
-    // TODO: Get all devices which are pending here
+  public async processPending(device: PubKey) {
+    const messages = this.pendingMessageCache.getForDevice(device);
+
+    const hasSession = SessionProtocol.hasSession(device);
+    const conversation = ConversationController.get(device.key);
+    const isMediumGroup = conversation.isMediumGroup();
+
+    if (!isMediumGroup && !hasSession) {
+      await SessionProtocol.sendSessionRequestIfNeeded(device);
+
+      return;
+    }
+
+    const jobQueue = this.getJobQueue(device);
+    messages.forEach(message => {
+      if (!jobQueue.has(message.identifier)) {
+        const promise = jobQueue.add(async () => MessageSender.send(message));
+
+        promise
+          .then(() => {
+            // Message sent; remove from cache
+            void this.pendingMessageCache.remove(message);
+          })
+          // Message failed to send
+          .catch(() => null);
+      }
+    });
   }
 
-  private queue(device: string, message: ContentMessage) {
-    // TODO: implement
+  private async processAllPending() {
+    const devices = this.pendingMessageCache.getDevices();
+    const promises = devices.map(async device => this.processPending(device));
+
+    return Promise.all(promises);
   }
 
-  private queueOpenGroupMessage(message: OpenGroupMessage) {
-    // TODO: Do we need to queue open group messages?
-    // If so we can get open group job queue and add the send job here
+  private async queue(device: PubKey, message: ContentMessage) {
+    if (message instanceof SessionRequestMessage) {
+      return;
+    }
+
+    await this.pendingMessageCache.add(device, message);
+    await this.processPending(device);
   }
 
-  private getJobQueue(device: string): JobQueue {
+  private getJobQueue(device: PubKey): JobQueue {
     let queue = this.jobQueues.get(device);
     if (!queue) {
       queue = new JobQueue();
@@ -57,4 +170,5 @@ export class MessageQueue implements MessageQueueInterface {
 
     return queue;
   }
+
 }
diff --git a/ts/session/sending/MessageQueueInterface.ts b/ts/session/sending/MessageQueueInterface.ts
index b160ce365..b4b374569 100644
--- a/ts/session/sending/MessageQueueInterface.ts
+++ b/ts/session/sending/MessageQueueInterface.ts
@@ -5,6 +5,7 @@ import {
 } from '../messages/outgoing';
 import { RawMessage } from '../types/RawMessage';
 import { TypedEventEmitter } from '../utils';
+import { PubKey } from '../types';
 
 type GroupMessageType = OpenGroupMessage | ClosedGroupMessage;
 
@@ -15,8 +16,8 @@ export interface MessageQueueInterfaceEvents {
 
 export interface MessageQueueInterface {
   events: TypedEventEmitter<MessageQueueInterfaceEvents>;
-  sendUsingMultiDevice(user: string, message: ContentMessage): void;
-  send(device: string, message: ContentMessage): void;
+  sendUsingMultiDevice(user: PubKey, message: ContentMessage): void;
+  send(device: PubKey, message: ContentMessage): void;
   sendToGroup(message: GroupMessageType): void;
-  sendSyncMessage(message: ContentMessage): void;
+  sendSyncMessage(message: ContentMessage, sendTo: Array<PubKey>): Promise<Array<void>>;
 }
diff --git a/ts/session/sending/PendingMessageCache.ts b/ts/session/sending/PendingMessageCache.ts
index 30bfe35d6..074ee8174 100644
--- a/ts/session/sending/PendingMessageCache.ts
+++ b/ts/session/sending/PendingMessageCache.ts
@@ -2,7 +2,7 @@ import { createOrUpdateItem, getItemById } from '../../../js/modules/data';
 import { PartialRawMessage, RawMessage } from '../types/RawMessage';
 import { ContentMessage } from '../messages/outgoing';
 import { PubKey } from '../types';
-import * as MessageUtils from '../utils';
+import { MessageUtils } from '../utils';
 
 // This is an abstraction for storing pending messages.
 // Ideally we want to store pending messages in the database so that
diff --git a/ts/session/types/PubKey.ts b/ts/session/types/PubKey.ts
index 5653db5b5..fc49b5472 100644
--- a/ts/session/types/PubKey.ts
+++ b/ts/session/types/PubKey.ts
@@ -1,7 +1,7 @@
 export class PubKey {
   public static readonly PUBKEY_LEN = 66;
-  private static readonly regex: string = `^05[0-9a-fA-F]{${PubKey.PUBKEY_LEN -
-    2}}$`;
+  private static readonly regex: RegExp = new RegExp(`^05[0-9a-fA-F]{${PubKey.PUBKEY_LEN -
+    2}}$`);
   public readonly key: string;
 
   constructor(pubkeyString: string) {
@@ -19,7 +19,7 @@ export class PubKey {
   }
 
   public static validate(pubkeyString: string): boolean {
-    if (pubkeyString.match(PubKey.regex)) {
+    if (this.regex.test(pubkeyString)) {
       return true;
     }
 
diff --git a/ts/session/utils/SyncMessageUtils.ts b/ts/session/utils/SyncMessageUtils.ts
new file mode 100644
index 000000000..6052a69cc
--- /dev/null
+++ b/ts/session/utils/SyncMessageUtils.ts
@@ -0,0 +1,80 @@
+import {
+  ContactSyncMessage,
+  ContentMessage,
+  SyncMessageEnum,
+} from '../messages/outgoing';
+import { PubKey } from '../types';
+
+import * as _ from 'lodash';
+import * as Data from '../../../js/modules/data';
+import { ConversationController, textsecure, Whisper } from '../../window';
+import { OpenGroup } from '../types/OpenGroup';
+
+
+export async function from(
+  message: ContentMessage,
+  sendTo: PubKey | OpenGroup,
+  syncType: SyncMessageEnum.CONTACTS | SyncMessageEnum.GROUPS = SyncMessageEnum.CONTACTS
+): Promise<ContactSyncMessage> {
+  const { timestamp, identifier } = message;
+
+  // Stubbed for now
+  return new ContactSyncMessage({
+    timestamp,
+    identifier,
+    contacts: [],
+  });
+}
+
+export async function canSync(message: ContentMessage): Promise<boolean> {
+  // This function should be agnostic to the device; it shouldn't need
+  // to know about the recipient
+  // return Boolean(from(message, device));
+  // Stubbed for now
+  return true;
+}
+
+export async function getSyncContacts(): Promise<Array<any>> {
+  const thisDevice = textsecure.storage.user.getNumber();
+  const primaryDevice = await Data.getPrimaryDeviceFor(thisDevice);
+  const conversations = await Data.getAllConversations({ ConversationCollection: Whisper.ConversationCollection });
+
+  // We are building a set of all contacts
+  const primaryContacts = conversations.filter(c =>
+    c.isPrivate() &&
+    !c.isOurLocalDevice() &&
+    c.isFriend() &&
+    !c.attributes.secondaryStatus
+  ) || [];
+
+  const secondaryContactsPartial = conversations.filter(c =>
+      c.isPrivate() &&
+      !c.isOurLocalDevice() &&
+      c.isFriend() &&
+      c.attributes.secondaryStatus
+  );
+
+  const seondaryContactsPromise = secondaryContactsPartial.map(async c =>
+    ConversationController.getOrCreateAndWait(
+      c.getPrimaryDevicePubKey(),
+      'private'
+    )
+  );
+
+  const secondaryContacts = (await Promise.all(seondaryContactsPromise))
+    // Filter out our primary key if it was added here
+    .filter(c => c.id !== primaryDevice);
+
+  // Return unique contacts
+  return _.uniqBy([
+    ...primaryContacts,
+    ...secondaryContacts,
+  ], device => !!device);
+}
+
+export async function getOurPairedDevices(): Promise<Array<PubKey>> {
+  const ourPubKey = textsecure.storage.user.getNumber();
+  const ourDevices = await Data.getPairedDevicesFor(ourPubKey);
+
+  return ourDevices.map(device => new PubKey(device));
+}
diff --git a/ts/session/utils/index.ts b/ts/session/utils/index.ts
index 96904245d..b5f9dd93e 100644
--- a/ts/session/utils/index.ts
+++ b/ts/session/utils/index.ts
@@ -1,3 +1,7 @@
+import * as MessageUtils from './Messages';
+import * as SyncMessageUtils from './SyncMessageUtils';
+
 export * from './TypedEmitter';
 export * from './JobQueue';
-export * from './Messages';
+
+export { MessageUtils, SyncMessageUtils };