diff --git a/CHANGES.md b/CHANGES.md
index b3741ee..48e0e5e 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -2,6 +2,12 @@ Release history
 ===============
 
 
+Version 0.1.8
+-------------
+
+ * Added an optional LRU cache
+
+
 Version 0.1.7
 -------------
 
diff --git a/README.md b/README.md
index 795916b..3cf2182 100644
--- a/README.md
+++ b/README.md
@@ -40,16 +40,31 @@ npm install wndb-with-exceptions --save
 API
 ---
 
-### new WordNet([directory])
+### new WordNet([options | string])
 
-The constructor returns a new object to access a WordNet database at the specified
-directory. If no directory is passed, the module uses `require` to locate 
-`wndb-with-exceptions`, so if you don't want to deploy your own WordNet, all you
-need to do is add `wndb-with-exceptions` as an application dependency and not 
-pass a directory to the constructor. 
+The constructor returns a new object to access a WordNet database. The passed 
+options configure the interface. The following options are available:
+
+ *  __dataDir__ -- specifies the location of the Wordnet directory. 
+
+    If this option isn't passed, the module uses `require` to locate 
+    `wndb-with-exceptions`, so if you don't want to deploy your own WordNet, all you
+    need to do is add `wndb-with-exceptions` as an application dependency and not 
+    pass a directory to the constructor. 
+    The original WordNet data files can always be manually downloaded and installed
+    anywhere from http://wordnet.princeton.edu/wordnet/download. 
+
+    As a shortcut, if you pass a string directly to the constructor, it's interpreted
+    as a Wordnet directory, and all other options default in sensible ways. 
+
+ *  __cache__ -- adds an LRU cache to the Wordnet access.
+
+    If the option is false, no cache is set; and if it is true, then a cache (using
+    `lru-cache` with a default size of 2000 items) is set. In addition, the cache can be
+    an object. If that object has a `get` method then it's used as a cache directly, and 
+    if it doesn't, it's assumed to be a configuration object which will be used to 
+    configure a new `lru-cache`.
 
-The original WordNet data files can always be manually downloaded and installed
-anywhere from http://wordnet.princeton.edu/wordnet/download. 
 
 ### lookup(word, callback)
 
diff --git a/lib/wordnet.js b/lib/wordnet.js
index 4cca0bf..fb03cf5 100644
--- a/lib/wordnet.js
+++ b/lib/wordnet.js
@@ -1,4 +1,4 @@
-var DataFile, IndexFile, Promise, WordNet, async, fs, path,
+var DataFile, IndexFile, LRU, Promise, WordNet, async, fs, path,
   __slice = [].slice;
 
 IndexFile = require('./index_file');
@@ -13,14 +13,25 @@ path = require('path');
 
 fs = require('fs');
 
+LRU = require('lru-cache');
+
 require('es6-shim');
 
 WordNet = (function() {
   var exceptions, forms, tokenDetach, unique, _forms, _loadExceptions, _validForms, _validFormsWithExceptions;
 
-  function WordNet(dataDir) {
+  function WordNet(options) {
     var WNdb, e;
-    if (!dataDir) {
+    if (typeof options === 'string') {
+      options = {
+        dataDir: options
+      };
+    } else {
+      if (options == null) {
+        options = {};
+      }
+    }
+    if (options.dataDir == null) {
       try {
         WNdb = require('wndb-with-exceptions');
       } catch (_error) {
@@ -28,17 +39,31 @@ WordNet = (function() {
         console.error("Please 'npm install wndb-with-exceptions' before using WordNet module or specify a dict directory.");
         throw e;
       }
-      dataDir = WNdb.path;
+      options.dataDir = WNdb.path;
+    }
+    if (!options.cache) {
+      this.cache = null;
+    } else {
+      if (options.cache === true) {
+        options.cache = {
+          max: 2000
+        };
+      }
+      if (typeof options.cache === 'object' && typeof options.cache.get === 'function') {
+        this.cache = options.cache;
+      } else {
+        this.cache = LRU(options.cache);
+      }
     }
-    this.path = dataDir;
-    this.nounIndex = new IndexFile(dataDir, 'noun');
-    this.verbIndex = new IndexFile(dataDir, 'verb');
-    this.adjIndex = new IndexFile(dataDir, 'adj');
-    this.advIndex = new IndexFile(dataDir, 'adv');
-    this.nounData = new DataFile(dataDir, 'noun');
-    this.verbData = new DataFile(dataDir, 'verb');
-    this.adjData = new DataFile(dataDir, 'adj');
-    this.advData = new DataFile(dataDir, 'adv');
+    this.path = options.dataDir;
+    this.nounIndex = new IndexFile(this.path, 'noun');
+    this.verbIndex = new IndexFile(this.path, 'verb');
+    this.adjIndex = new IndexFile(this.path, 'adj');
+    this.advIndex = new IndexFile(this.path, 'adv');
+    this.nounData = new DataFile(this.path, 'noun');
+    this.verbData = new DataFile(this.path, 'verb');
+    this.adjData = new DataFile(this.path, 'adj');
+    this.advData = new DataFile(this.path, 'adv');
     this.allFiles = [
       {
         index: this.nounIndex,
@@ -61,9 +86,21 @@ WordNet = (function() {
   }
 
   WordNet.prototype.get = function(synsetOffset, pos, callback) {
-    var dataFile;
-    dataFile = this.getDataFile(pos);
-    return dataFile.get(synsetOffset, callback);
+    var dataFile, hit, query, wordnet;
+    wordnet = this;
+    if (this.cache) {
+      query = "get:" + synsetOffset + ":" + pos;
+      if (hit = wordnet.cache.get(query)) {
+        return callback(hit);
+      }
+    }
+    dataFile = wordnet.getDataFile(pos);
+    return dataFile.get(synsetOffset, function(result) {
+      if (query) {
+        wordnet.cache.set(query, result);
+      }
+      return callback(result);
+    });
   };
 
   WordNet.prototype.getAsync = function(synsetOffset, pos) {
@@ -77,14 +114,25 @@ WordNet = (function() {
   };
 
   WordNet.prototype.lookup = function(input, callback) {
-    var lword, pos, selectedFiles, word, wordnet, _ref;
+    var hit, lword, pos, query, selectedFiles, word, wordnet, _ref;
     wordnet = this;
     _ref = input.split('#'), word = _ref[0], pos = _ref[1];
     lword = word.toLowerCase().replace(/\s+/g, '_');
+    if (this.cache) {
+      query = "lookup:" + input;
+      if (hit = wordnet.cache.get(query)) {
+        return callback(hit);
+      }
+    }
     selectedFiles = !pos ? wordnet.allFiles : wordnet.allFiles.filter(function(file) {
       return file.pos === pos;
     });
-    return wordnet.lookupFromFiles(selectedFiles, [], lword, callback);
+    return wordnet.lookupFromFiles(selectedFiles, [], lword, function(results) {
+      if (query) {
+        wordnet.cache.set(query, results);
+      }
+      return callback(results);
+    });
   };
 
   WordNet.prototype.lookupAsync = function(input, callback) {
@@ -98,9 +146,15 @@ WordNet = (function() {
   };
 
   WordNet.prototype.findSense = function(input, callback) {
-    var lword, pos, selectedFiles, sense, senseNumber, word, wordnet, _ref;
+    var hit, lword, pos, query, selectedFiles, sense, senseNumber, word, wordnet, _ref;
     wordnet = this;
     _ref = input.split('#'), word = _ref[0], pos = _ref[1], senseNumber = _ref[2];
+    if (this.cache) {
+      query = "findSense:" + input;
+      if (hit = wordnet.cache.get(query)) {
+        return callback(hit);
+      }
+    }
     sense = parseInt(senseNumber);
     if (Number.isNaN(sense)) {
       throw new Error("Sense number should be an integer");
@@ -112,7 +166,12 @@ WordNet = (function() {
       return file.pos === pos;
     });
     return wordnet.lookupFromFiles(selectedFiles, [], lword, function(response) {
-      return callback(response[sense - 1]);
+      var result;
+      result = response[sense - 1];
+      if (query) {
+        wordnet.cache.set(query, result);
+      }
+      return callback(result);
     });
   };
 
@@ -127,9 +186,15 @@ WordNet = (function() {
   };
 
   WordNet.prototype.querySense = function(input, callback) {
-    var pos, word, wordnet, _ref;
+    var hit, pos, query, word, wordnet, _ref;
     wordnet = this;
     _ref = input.split('#'), word = _ref[0], pos = _ref[1];
+    if (this.cache) {
+      query = "querySense:" + input;
+      if (hit = wordnet.cache.get(query)) {
+        return callback(hit);
+      }
+    }
     return wordnet.lookup(input, function(results) {
       var i, sense, senseCounts, senses;
       senseCounts = {};
@@ -149,6 +214,9 @@ WordNet = (function() {
         }
         return _results;
       })();
+      if (query) {
+        wordnet.cache.set(query, senses);
+      }
       return callback(senses);
     });
   };
@@ -502,7 +570,20 @@ WordNet = (function() {
   };
 
   WordNet.prototype.validForms = function(string, callback) {
-    return _validFormsWithExceptions(this, string, callback);
+    var hit, query, wordnet;
+    wordnet = this;
+    if (this.cache) {
+      query = "validForms:" + string;
+      if (hit = wordnet.cache.get(query)) {
+        return callback(hit);
+      }
+    }
+    return _validFormsWithExceptions(this, string, function(result) {
+      if (query) {
+        wordnet.cache.set(query, result);
+      }
+      return callback(result);
+    });
   };
 
   WordNet.prototype.validFormsAsync = function(string) {
diff --git a/package.json b/package.json
index ce82777..a58aa3d 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "node-wordnet",
-  "version": "0.1.7",
+  "version": "0.1.8",
   "description": "Node.js interface for Wordnet",
   "main": "lib/wordnet.js",
   "scripts": {
@@ -31,6 +31,7 @@
   "dependencies": {
     "async": "^0.9.0",
     "bluebird": "^2.6.0",
-    "es6-shim": "^0.22.1"
+    "es6-shim": "^0.22.1",
+    "lru-cache": "^2.5.0"
   }
 }
diff --git a/src/wordnet.coffee b/src/wordnet.coffee
index 76efc73..9f6013e 100644
--- a/src/wordnet.coffee
+++ b/src/wordnet.coffee
@@ -26,39 +26,63 @@
 ## (5) - move to use wndb-with-exceptions instead of WNdb, to provide morphological exceptions
 ## (6) - significant improvements in testing
 
-IndexFile = require('./index_file')
-DataFile = require('./data_file')
+IndexFile = require './index_file'
+DataFile =  require './data_file'
 
-async = require('async')
-Promise = require('bluebird')
-path = require('path')
-fs = require('fs')
+async =     require 'async'
+Promise =   require 'bluebird'
+path =      require 'path'
+fs =        require 'fs'
+
+LRU =       require 'lru-cache'
 
 require('es6-shim')
 
 class WordNet
 
-  constructor: (dataDir) ->
+  constructor: (options) ->
+
+    ## For compatibility, if the options are a string, it's just the Wordnet path
+    if typeof options == 'string'
+      options = {dataDir: options}
+    else
+      options ?= {}
 
-    if !dataDir
+
+    if ! options.dataDir?
       try
         WNdb = require('wndb-with-exceptions')
       catch e
         console.error("Please 'npm install wndb-with-exceptions' before using WordNet module or specify a dict directory.")
         throw e
-      dataDir = WNdb.path
+      options.dataDir = WNdb.path
+
+
+    if ! options.cache
+      @cache = null
+    else
+      if options.cache == true
+        options.cache = {
+          max: 2000
+        }
+
+      if typeof options.cache == 'object' and typeof options.cache.get == 'function'
+        @cache = options.cache
+      else
+        @cache = LRU options.cache
 
-    @path = dataDir
 
-    @nounIndex = new IndexFile(dataDir, 'noun')
-    @verbIndex = new IndexFile(dataDir, 'verb')
-    @adjIndex = new IndexFile(dataDir, 'adj')
-    @advIndex = new IndexFile(dataDir, 'adv')
+    @path = options.dataDir
 
-    @nounData = new DataFile(dataDir, 'noun')
-    @verbData = new DataFile(dataDir, 'verb')
-    @adjData = new DataFile(dataDir, 'adj')
-    @advData = new DataFile(dataDir, 'adv')
+    @nounIndex = new IndexFile(@path, 'noun')
+    @verbIndex = new IndexFile(@path, 'verb')
+    @adjIndex = new IndexFile(@path, 'adj')
+    @advIndex = new IndexFile(@path, 'adv')
+
+    @nounData = new DataFile(@path, 'noun')
+    @verbData = new DataFile(@path, 'verb')
+    @adjData = new DataFile(@path, 'adj')
+    @advData = new DataFile(@path, 'adv')
 
     @allFiles = [
       {index: @nounIndex, data: @nounData, pos: 'n'}
@@ -68,8 +92,16 @@ class WordNet
     ]
 
   get: (synsetOffset, pos, callback) ->
-    dataFile = @getDataFile(pos)
-    dataFile.get synsetOffset, callback
+    wordnet = @
+
+    if @cache
+      query = "get:#{synsetOffset}:#{pos}"
+      return callback(hit) if hit = wordnet.cache.get query
+
+    dataFile = wordnet.getDataFile(pos)
+    dataFile.get synsetOffset, (result) ->
+      wordnet.cache.set query, result if query
+      callback(result)
 
   getAsync: (synsetOffset, pos) ->
     wordnet = @
@@ -82,8 +114,14 @@ class WordNet
     [word, pos] = input.split('#')
     lword = word.toLowerCase().replace(/\s+/g, '_')
 
+    if @cache
+      query = "lookup:#{input}"
+      return callback(hit) if hit = wordnet.cache.get query
+
     selectedFiles = if ! pos then wordnet.allFiles else wordnet.allFiles.filter (file) -> file.pos == pos
-    wordnet.lookupFromFiles selectedFiles, [], lword, callback
+    wordnet.lookupFromFiles selectedFiles, [], lword, (results) ->
+      wordnet.cache.set query, results if query
+      callback(results)
 
   lookupAsync: (input, callback) ->
     wordnet = @
@@ -95,6 +133,10 @@ class WordNet
     wordnet = @
     [word, pos, senseNumber] = input.split('#')
 
+    if @cache
+      query = "findSense:#{input}"
+      return callback(hit) if hit = wordnet.cache.get query
+
     sense = parseInt(senseNumber)
     if Number.isNaN(sense)
       throw new Error("Sense number should be an integer")
@@ -104,7 +146,9 @@ class WordNet
     lword = word.toLowerCase().replace(/\s+/g, '_')
     selectedFiles = wordnet.allFiles.filter (file) -> file.pos == pos
     wordnet.lookupFromFiles selectedFiles, [], lword, (response) ->
-      callback(response[sense - 1])
+      result = response[sense - 1]
+      wordnet.cache.set query, result if query
+      callback(result)
 
   findSenseAsync: (input) ->
     wordnet = @
@@ -116,6 +160,10 @@ class WordNet
     wordnet = @
     [word, pos] = input.split('#')
 
+    if @cache
+      query = "querySense:#{input}"
+      return callback(hit) if hit = wordnet.cache.get query
+
     wordnet.lookup input, (results)  ->
       senseCounts = {}
       senses = for sense, i in results
@@ -124,6 +172,7 @@ class WordNet
         senseCounts[pos] ?= 1
         word + "#" + pos + "#" + senseCounts[pos]++
 
+      wordnet.cache.set query, senses if query
       callback(senses)
 
   querySenseAsync: (input) ->
@@ -389,7 +438,15 @@ class WordNet
 
 
   validForms: (string, callback) ->
-    _validFormsWithExceptions @, string, callback
+    wordnet = @
+    
+    if @cache
+      query = "validForms:#{string}"
+      return callback(hit) if hit = wordnet.cache.get query
+
+    _validFormsWithExceptions @, string, (result) ->
+      wordnet.cache.set query, result if query
+      callback(result)
 
   validFormsAsync: (string) ->
     new Promise (resolve, reject) =>
diff --git a/test/wordnet_cache_test.coffee b/test/wordnet_cache_test.coffee
new file mode 100644
index 0000000..5235259
--- /dev/null
+++ b/test/wordnet_cache_test.coffee
@@ -0,0 +1,94 @@
+chai = require('chai')
+chai.use(require('chai-as-promised'))
+should = chai.should()
+
+async = require('async')
+
+Wordnet = require('../lib/wordnet')
+
+describe 'wordnet with cache enabled', () ->
+
+  wordnet = undefined
+
+  beforeEach (done) ->
+    wordnet = new Wordnet({cache: true})
+    done()
+
+  describe 'get', () ->
+    it 'should succeed', (done) ->
+      wordnet.get 3827107, 'n', (results) ->
+        should.exist(results)
+        results.should.have.property('gloss', '(computer science) any computer that is hooked up to a computer network  ')
+        done()
+        
+    it 'should return the exact same value for a second query', (done) ->
+      wordnet.get 3827107, 'n', (results) ->
+        should.exist(results)
+        wordnet.get 3827107, 'n', (results2) ->
+          (results == results2).should.be.true
+          done()
+
+
+  describe 'lookup', () ->
+    it 'should succeed for node', (done) ->
+      wordnet.lookup 'node', (results) ->
+        should.exist(results)
+        results.should.be.an.instanceOf(Array)
+        results[0].should.have.property('synsetOffset', 3827107)
+        done()
+
+    it 'should return the exact same value for a second query', (done) ->
+      wordnet.lookup 'node', (results) ->
+        should.exist(results)
+        wordnet.lookup 'node', (results2) ->
+          (results == results2).should.be.true
+          done()
+
+
+  describe 'findSense', () ->
+
+    it 'should succeed for lie#v#1', (done) ->
+      wordnet.findSense 'lie#v#1', (results) ->
+        should.exist(results)
+        results.should.have.property('lemma', 'lie_down')
+        results.should.have.property('pos', 'v')
+        done()
+
+    it 'should return the exact same value for a second query', (done) ->
+      wordnet.findSense 'lie#v#1', (results) ->
+        should.exist(results)
+        wordnet.findSense 'lie#v#1', (results2) ->
+          (results == results2).should.be.true
+          done()
+
+
+  describe 'querySense', () ->
+    it 'should succeed for node', (done) ->
+      wordnet.querySense 'node', (results) ->
+        should.exist(results)
+        results.should.be.an.instanceOf(Array)
+        results.should.have.length(8)
+        done()
+
+    it 'should return the exact same value for a second query', (done) ->
+      wordnet.querySense 'node', (results) ->
+        should.exist(results)
+        wordnet.querySense 'node', (results2) ->
+          (results == results2).should.be.true
+          done()
+
+
+  describe 'validForms', () ->
+
+    it 'should succeed for axes#n', (done) ->
+      wordnet.validForms 'axes#n', (results) ->
+        should.exist(results)
+        results.should.eql(['ax#n', 'axis#n'])
+        done()
+
+    it 'should return the exact same value for a second query', (done) ->
+      wordnet.validForms 'axes#n', (results) ->
+        should.exist(results)
+        wordnet.validForms 'axes#n', (results2) ->
+          (results == results2).should.be.true
+          done()