diff --git a/lib/client.js b/lib/client.js
index fde7b2d..8422ad0 100644
--- a/lib/client.js
+++ b/lib/client.js
@@ -40,6 +40,7 @@ extend(Raven.prototype, {
 
     this.loggerName = options.logger || '';
     this.dataCallback = options.dataCallback;
+    this.shouldSendCallback = options.shouldSendCallback;
 
     if (!this.dsn) {
       utils.consoleAlert('no DSN provided, error reporting disabled');
@@ -80,6 +81,7 @@ extend(Raven.prototype, {
   process: function process(eventId, kwargs, cb) {
     // prod codepaths shouldn't hit this branch, for testing
     if (typeof eventId === 'object') {
+      cb = kwargs;
       kwargs = eventId;
       eventId = this.generateEventId();
     }
@@ -114,9 +116,14 @@ extend(Raven.prototype, {
       kwargs = this.dataCallback(kwargs);
     }
 
-    if (this._enabled) {
+    var shouldSend = true;
+    if (!this._enabled) shouldSend = false;
+    if (this.shouldSendCallback && !this.shouldSendCallback()) shouldSend = false;
+
+    if (shouldSend) {
       this.send(kwargs, cb);
     } else {
+      // wish there was a good way to communicate to cb why we didn't send; worth considering cb api change?
       setImmediate(function () {
         cb(null, eventId);
       });
@@ -309,6 +316,41 @@ extend(Raven.prototype, {
     utils.consoleAlert('setTagsContext has been deprecated and will be removed in v2.0');
     this._globalContext.tags = extend({}, this._globalContext.tags, tags);
     return this;
+  },
+
+  setCallbackHelper: function (propertyName, callback) {
+    var original = this[propertyName];
+    if (typeof callback === 'function') {
+      this[propertyName] = function (data) {
+        return callback(data, original);
+      };
+    } else {
+      this[propertyName] = callback;
+    }
+
+    return this;
+  },
+
+  /*
+   * Set the dataCallback option
+   *
+   * @param {function} callback The callback to run which allows the
+   *                            data blob to be mutated before sending
+   * @return {Raven}
+   */
+  setDataCallback: function (callback) {
+    return this.setCallbackHelper('dataCallback', callback);
+  },
+
+  /*
+   * Set the shouldSendCallback option
+   *
+   * @param {function} callback The callback to run which allows
+   *                            introspecting the blob before sending
+   * @return {Raven}
+   */
+  setShouldSendCallback: function (callback) {
+    return this.setCallbackHelper('shouldSendCallback', callback);
   }
 });
 
diff --git a/test/raven.client.js b/test/raven.client.js
index 6aa548c..0219909 100644
--- a/test/raven.client.js
+++ b/test/raven.client.js
@@ -382,6 +382,24 @@ describe('raven.Client', function () {
       });
     });
 
+    it('should respect shouldSendCallback', function (done) {
+      client = new raven.Client(dsn, {
+        shouldSendCallback: function (data) {
+          return false;
+        }
+      });
+
+      // neither of these should fire, so report err to done if they do
+      client.on('logged', done);
+      client.on('error', done);
+
+      client.process({
+        message: 'test'
+      }, function (err, eventId) {
+        setTimeout(done, 10);
+      });
+    });
+
     it('should attach environment', function (done) {
       client = new raven.Client(dsn, {
         environment: 'staging'