diff --git a/src/js/account.js b/src/js/account.js
index 2e1121e5..dcc14c67 100644
--- a/src/js/account.js
+++ b/src/js/account.js
@@ -128,6 +128,22 @@ Account.prototype.entry = function (callback)
   return this;
 };
 
+/**
+ * Notify object of a relevant transaction.
+ *
+ * This is only meant to be called by the Remote class. You should never have to
+ * call this yourself.
+ */
+Account.prototype.notifyTx = function (message)
+{
+  // Only trigger the event if the account object is actually
+  // subscribed - this prevents some weird phantom events from
+  // occurring.
+  if (this._subs) {
+    this.emit('transaction', message);
+  }
+};
+
 exports.Account	    = Account;
 
 // vim:sw=2:sts=2:ts=8:et
diff --git a/src/js/currency.js b/src/js/currency.js
index ab960418..22bd112f 100644
--- a/src/js/currency.js
+++ b/src/js/currency.js
@@ -22,9 +22,9 @@ Currency.json_rewrite = function (j) {
 };
 
 Currency.from_json = function (j) {
-  return 'string' === typeof j
-      ? (new Currency()).parse_json(j)
-      : j.clone();
+  if (j instanceof Currency) return j.clone();
+  else if ('string' === typeof j) return (new Currency()).parse_json(j);
+  else return new Currency(); // NaN
 };
 
 Currency.is_valid = function (j) {
diff --git a/src/js/index.js b/src/js/index.js
index b603d6a5..05ec1f84 100644
--- a/src/js/index.js
+++ b/src/js/index.js
@@ -1,5 +1,6 @@
 exports.Remote = require('./remote').Remote;
 exports.Amount = require('./amount').Amount;
+exports.Currency = require('./currency').Currency;
 exports.UInt160 = require('./amount').UInt160;
 exports.Seed = require('./amount').Seed;
 
diff --git a/src/js/meta.js b/src/js/meta.js
index 46c0e46c..23ba8152 100644
--- a/src/js/meta.js
+++ b/src/js/meta.js
@@ -1,4 +1,5 @@
 var extend = require('extend');
+var utils = require('./utils');
 var UInt160 = require('./uint160').UInt160;
 var Amount = require('./amount').Amount;
 
@@ -102,7 +103,35 @@ Meta.prototype.getAffectedAccounts = function ()
     }
   });
 
+  accounts = utils.arrayUnique(accounts);
+
   return accounts;
 };
 
+Meta.prototype.getAffectedBooks = function ()
+{
+  var books = [];
+
+  this.each(function (an) {
+    if (an.entryType !== 'Offer') return;
+
+    var gets = Amount.from_json(an.fields.TakerGets);
+    var pays = Amount.from_json(an.fields.TakerPays);
+
+    var getsKey = gets.currency().to_json();
+    if (getsKey !== 'XRP') getsKey += '/' + gets.issuer().to_json();
+
+    var paysKey = pays.currency().to_json();
+    if (paysKey !== 'XRP') paysKey += '/' + pays.issuer().to_json();
+
+    var key = getsKey + ":" + paysKey;
+
+    books.push(key);
+  });
+
+  books = utils.arrayUnique(books);
+
+  return books;
+};
+
 exports.Meta = Meta;
diff --git a/src/js/orderbook.js b/src/js/orderbook.js
index 00ac29b2..535919ec 100644
--- a/src/js/orderbook.js
+++ b/src/js/orderbook.js
@@ -1,6 +1,10 @@
 // Routines for working with an orderbook.
 //
+// One OrderBook object represents one half of an order book. (i.e. bids OR
+// asks) Which one depends on the ordering of the parameters.
+//
 // Events:
+//  - transaction   A transaction that affects the order book.
 
 // var network = require("./network.js");
 
@@ -12,28 +16,29 @@ var Currency = require('./currency').Currency;
 var extend = require('extend');
 
 var OrderBook = function (remote,
-                          currency_out, issuer_out,
-                          currency_in,  issuer_in) {
+                          currency_gets, issuer_gets,
+                          currency_pays, issuer_pays) {
   var self = this;
 
   this._remote = remote;
-  this._currency_out = currency_out;
-  this._issuer_out = issuer_out;
-  this._currency_in = currency_in;
-  this._issuer_in = issuer_in;
+  this._currency_gets = currency_gets;
+  this._issuer_gets = issuer_gets;
+  this._currency_pays = currency_pays;
+  this._issuer_pays = issuer_pays;
 
   this._subs = 0;
 
-  // Ledger entry object
-  // Important: This must never be overwritten, only extend()-ed
-  this._entry = {};
+  // We consider ourselves synchronized if we have a current copy of the offers,
+  // we are online and subscribed to updates.
+  this._sync = false;
+
+  // Offers
+  this._offers = [];
 
   this.on('newListener', function (type, listener) {
     if (OrderBook.subscribe_events.indexOf(type) !== -1) {
       if (!self._subs && 'open' === self._remote._online_state) {
-        self._remote.request_subscribe()
-          .books([self.to_json()], true)
-          .request();
+        self._subscribe();
       }
       self._subs  += 1;
     }
@@ -44,6 +49,7 @@ var OrderBook = function (remote,
       self._subs  -= 1;
 
       if (!self._subs && 'open' === self._remote._online_state) {
+        self._sync = false;
         self._remote.request_unsubscribe()
           .books([self.to_json()])
           .request();
@@ -59,6 +65,10 @@ var OrderBook = function (remote,
     }
   });
 
+  this._remote.on('disconnect', function () {
+    self._sync = false;
+  });
+
   return this;
 };
 
@@ -67,17 +77,42 @@ OrderBook.prototype = new EventEmitter;
 /**
  * List of events that require a remote subscription to the orderbook.
  */
-OrderBook.subscribe_events = ['transaction'];
+OrderBook.subscribe_events = ['transaction', 'model'];
+
+/**
+ * Subscribes to orderbook.
+ *
+ * @private
+ */
+OrderBook.prototype._subscribe = function ()
+{
+  var self = this;
+  self._remote.request_subscribe()
+    .books([self.to_json()], true)
+    .on('error', function () {
+      // XXX What now?
+    })
+    .on('success', function (res) {
+      self._sync = true;
+      self._offers = res.offers;
+      self.emit('model', self._offers);
+    })
+    .request();
+};
 
 OrderBook.prototype.to_json = function ()
 {
   var json = {
-    "CurrencyOut": this._currency_out,
-    "CurrencyIn": this._currency_in
+    "taker_gets": {
+      "currency": this._currency_gets
+    },
+    "taker_pays": {
+      "currency": this._currency_pays
+    }
   };
 
-  if (json["CurrencyOut"] !== "XRP") json["IssuerOut"] = this._issuer_out;
-  if (json["CurrencyIn"] !== "XRP")  json["IssuerIn"]  = this._issuer_in;
+  if (this._currency_gets !== "XRP") json["taker_gets"]["issuer"] = this._issuer_gets;
+  if (this._currency_pays !== "XRP") json["taker_pays"]["issuer"] = this._issuer_pays;
 
   return json;
 };
@@ -90,15 +125,108 @@ OrderBook.prototype.to_json = function ()
  */
 OrderBook.prototype.is_valid = function ()
 {
+  // XXX Should check for same currency (non-native) && same issuer
   return (
-    Currency.is_valid(this._currency_in) &&
-    (this._currency_in !== "XRP" && UInt160.is_valid(this._issuer_in)) &&
-    Currency.is_valid(this._currency_out) &&
-    (this._currency_out !== "XRP" && UInt160.is_valid(this._issuer_out)) &&
-    !(this._currency_in === "XRP" && this._currency_out === "XRP")
+    Currency.is_valid(this._currency_pays) &&
+    (this._currency_pays === "XRP" || UInt160.is_valid(this._issuer_pays)) &&
+    Currency.is_valid(this._currency_gets) &&
+    (this._currency_gets === "XRP" || UInt160.is_valid(this._issuer_gets)) &&
+    !(this._currency_pays === "XRP" && this._currency_gets === "XRP")
   );
 };
 
+/**
+ * Notify object of a relevant transaction.
+ *
+ * This is only meant to be called by the Remote class. You should never have to
+ * call this yourself.
+ */
+OrderBook.prototype.notifyTx = function (message)
+{
+  var self = this;
+
+  var changed = false;
+
+  message.mmeta.each(function (an) {
+    if (an.entryType !== 'Offer') return;
+
+    var i, l, offer;
+    if (an.diffType === 'DeletedNode' ||
+        an.diffType === 'ModifiedNode') {
+      for (i = 0, l = self._offers.length; i < l; i++) {
+        offer = self._offers[i];
+        console.log(offer.index, an.ledgerIndex);
+        if (offer.index === an.ledgerIndex) {
+          if (an.diffType === 'DeletedNode') {
+            self._offers.splice(i, 1);
+            console.log('node removed');
+          }
+          else extend(offer, an.fieldsFinal);
+          changed = true;
+          break;
+        }
+      }
+    } else if (an.diffType === 'CreatedNode') {
+      var price = Amount.from_json(an.fields.TakerPays).ratio_human(an.fields.TakerGets);
+      for (i = 0, l = self._offers.length; i < l; i++) {
+        offer = self._offers[i];
+        var priceItem = Amount.from_json(offer.TakerPays).ratio_human(offer.TakerGets);
+        console.log(price.to_text_full(), priceItem.to_text_full());
+        if (price.compareTo(priceItem) <= 0) {
+          var obj = an.fields;
+          obj.index = an.ledgerIndex;
+          self._offers.splice(i, 0, an.fields);
+          changed = true;
+          break;
+        }
+      }
+    }
+  });
+
+  // Only trigger the event if the account object is actually
+  // subscribed - this prevents some weird phantom events from
+  // occurring.
+  if (this._subs) {
+    this.emit('transaction', message);
+    if (changed) this.emit('model', this._offers);
+  }
+};
+
+/**
+ * Get offers model asynchronously.
+ *
+ * This function takes a callback and calls it with an array containing the
+ * current set of offers in this order book.
+ *
+ * If the data is available immediately, the callback may be called synchronously.
+ */
+OrderBook.prototype.offers = function (callback)
+{
+  var self = this;
+
+  if ("function" === typeof callback) {
+    if (this._sync) {
+      callback(this._offers);
+    } else {
+      this.once('model', function (offers) {
+        callback(offers);
+      });
+    }
+  }
+  return this;
+};
+
+/**
+ * Return latest known offers.
+ *
+ * Usually, this will just be an empty array if the order book hasn't been
+ * loaded yet. But this accessor may be convenient in some circumstances.
+ */
+OrderBook.prototype.offersSync = function ()
+{
+  return this._offers;
+};
+
 exports.OrderBook	    = OrderBook;
 
 // vim:sw=2:sts=2:ts=8:et
diff --git a/src/js/remote.js b/src/js/remote.js
index fed02525..25c6d7a2 100644
--- a/src/js/remote.js
+++ b/src/js/remote.js
@@ -208,20 +208,25 @@ Request.prototype.books = function (books, state) {
 
   for (var i = 0, l = books.length; i < l; i++) {
     var book = books[i];
+    var json = {};
 
-    var json = {
-      "CurrencyOut": Currency.json_rewrite(book["CurrencyOut"]),
-      "CurrencyIn": Currency.json_rewrite(book["CurrencyIn"])
-    };
+    function process(side) {
+      if (!book[side]) throw new Error("Missing "+side);
 
-    if (json["CurrencyOut"] !== "XRP") {
-      json["IssuerOut"] = UInt160.json_rewrite(book["IssuerOut"]);
-    }
-    if (json["CurrencyIn"] !== "XRP") {
-      json["IssuerIn"]  = UInt160.json_rewrite(book["IssuerIn"]);
+      var obj = {};
+      obj["currency"] = Currency.json_rewrite(book[side]["currency"]);
+      if (obj["currency"] !== "XRP") {
+        obj.issuer = UInt160.json_rewrite(book[side]["issuer"]);
+      }
+
+      json[side] = obj;
     }
 
-    if (state || book["StateNow"]) json["StateNow"] = true;
+    process("taker_gets");
+    process("taker_pays");
+
+    if (state || book["state_now"]) json["state_now"] = true;
+    if (book["both_sides"]) json["both_sides"] = true;
 
     procBooks.push(json);
   }
@@ -280,6 +285,7 @@ var Remote = function (opts, trace) {
   this._reserve_base          = undefined;
   this._reserve_inc           = undefined;
   this._server_status         = undefined;
+  this._last_tx               = null;
 
   // Local signing implies local fees and sequences
   if (this.local_signing) {
@@ -300,6 +306,9 @@ var Remote = function (opts, trace) {
   // Hash map of Account objects by AccountId.
   this._accounts = {};
 
+  // Hash map of OrderBook objects
+  this._books = {};
+
   // List of secrets that we know about.
   this.secrets = {
     // Secrets can be set by calling set_secret(account, secret).
@@ -629,7 +638,10 @@ Remote.prototype._connect_message = function (ws, json) {
         // unsubscribes will be added as needed.
         // XXX If not trusted, need proof.
 
-        // XXX Should de-duplicate transaction events
+        // De-duplicate transactions that are immediately following each other
+        // XXX Should have a cache of n txs so we can dedup out of order txs
+        if (this._last_tx === message.transaction.hash) break;
+        this._last_tx = message.transaction.hash;
 
         if (this.trace) utils.logObject("remote: tx: %s", message);
 
@@ -641,12 +653,15 @@ Remote.prototype._connect_message = function (ws, json) {
         for (var i = 0, l = affected.length; i < l; i++) {
           var account = self._accounts[affected[i]];
 
-          // Only trigger the event if the account object is actually
-          // subscribed - this prevents some weird phantom events from
-          // occurring.
-          if (account && account._subs) {
-            account.emit('transaction', message);
-          }
+          if (account) account.notifyTx(message);
+        }
+
+        // Pass the event on to any related OrderBooks
+        affected = message.mmeta.getAffectedBooks();
+        for (i = 0, l = affected.length; i < l; i++) {
+          var book = self._books[affected[i]];
+
+          if (book) book.notifyTx(message);
         }
 
         this.emit('transaction', message);
@@ -1143,13 +1158,26 @@ Remote.prototype.account = function (accountId) {
   return this._accounts[accountId];
 };
 
-Remote.prototype.book = function (currency_out, issuer_out,
-                                  currency_in,  issuer_in) {
-  var book = new OrderBook(this,
-                           currency_out, issuer_out,
-                           currency_in,  issuer_in);
+Remote.prototype.book = function (currency_gets, issuer_gets,
+                                  currency_pays, issuer_pays) {
+  var gets = currency_gets;
+  if (gets !== 'XRP') gets += '/' + issuer_gets;
+  var pays = currency_pays;
+  if (pays !== 'XRP') pays += '/' + issuer_pays;
 
-  return book;
+  var key = gets + ":" + pays;
+
+  if (!this._books[key]) {
+    var book = new OrderBook(this,
+                             currency_gets, issuer_gets,
+                             currency_pays, issuer_pays);
+
+    if (!book.is_valid()) return book;
+
+    this._books[key] = book;
+  }
+
+  return this._books[key];
 }
 
 // Return the next account sequence if possible.
diff --git a/src/js/utils.js b/src/js/utils.js
index 462f3f28..eafa8bea 100644
--- a/src/js/utils.js
+++ b/src/js/utils.js
@@ -97,6 +97,21 @@ var assert = function (assertion, msg) {
   }
 };
 
+/**
+ * Return unique values in array.
+ */
+var arrayUnique = function (arr) {
+  var u = {}, a = [];
+  for (var i = 0, l = arr.length; i < l; ++i){
+    if (u.hasOwnProperty(arr[i])) {
+      continue;
+    }
+    a.push(arr[i]);
+    u[arr[i]] = 1;
+  }
+  return a;
+};
+
 /**
  * Convert a ripple epoch to a JavaScript timestamp.
  *
@@ -115,6 +130,7 @@ exports.stringToHex   = stringToHex;
 exports.chunkString   = chunkString;
 exports.logObject     = logObject;
 exports.assert        = assert;
+exports.arrayUnique   = arrayUnique;
 exports.toTimestamp   = toTimestamp;
 
 // vim:sw=2:sts=2:ts=8:et