diff --git a/lib/chai/interface/expect.js b/lib/chai/interface/expect.js
index b827df7da..89f9efd52 100644
--- a/lib/chai/interface/expect.js
+++ b/lib/chai/interface/expect.js
@@ -8,5 +8,26 @@ module.exports = function (chai, util) {
   chai.expect = function (val, message) {
     return new chai.Assertion(val, message);
   };
-};
 
+  /**
+   * ### .fail(actual, expected, [message], [operator])
+   *
+   * Throw a failure.
+   *
+   * @name fail
+   * @param {Mixed} actual
+   * @param {Mixed} expected
+   * @param {String} message
+   * @param {String} operator
+   * @api public
+   */
+
+  chai.expect.fail = function (actual, expected, message, operator) {
+    message = message || 'expect.fail()';
+    throw new chai.AssertionError(message, {
+        actual: actual
+      , expected: expected
+      , operator: operator
+    }, chai.expect.fail);
+  };
+};
diff --git a/lib/chai/interface/should.js b/lib/chai/interface/should.js
index ddf4495b0..2b38f9a54 100644
--- a/lib/chai/interface/should.js
+++ b/lib/chai/interface/should.js
@@ -40,6 +40,28 @@ module.exports = function (chai, util) {
 
     var should = {};
 
+    /**
+     * ### .fail(actual, expected, [message], [operator])
+     *
+     * Throw a failure.
+     *
+     * @name fail
+     * @param {Mixed} actual
+     * @param {Mixed} expected
+     * @param {String} message
+     * @param {String} operator
+     * @api public
+     */
+
+    should.fail = function (actual, expected, message, operator) {
+      message = message || 'should.fail()';
+      throw new chai.AssertionError(message, {
+          actual: actual
+        , expected: expected
+        , operator: operator
+      }, should.fail);
+    };
+
     should.equal = function (val1, val2, msg) {
       new Assertion(val1, msg).to.equal(val2);
     };
diff --git a/test/expect.js b/test/expect.js
index e1e2f4d8f..9db12dee0 100644
--- a/test/expect.js
+++ b/test/expect.js
@@ -10,6 +10,12 @@ describe('expect', function () {
     expect('foo').to.equal('foo');
   });
 
+  it('fail', function () {
+    err(function() {
+      expect.fail(0, 1, 'this has failed');
+    }, /this has failed/);
+  });
+
   it('true', function(){
     expect(true).to.be.true;
     expect(false).to.not.be.true;
diff --git a/test/should.js b/test/should.js
index 7d96f828b..4c18e03b0 100644
--- a/test/should.js
+++ b/test/should.js
@@ -7,6 +7,12 @@ describe('should', function() {
     should.not.equal('foo', 'bar');
   });
 
+  it('fail', function () {
+    err(function() {
+      should.fail(0, 1, 'this has failed');
+    }, 'this has failed');
+  });
+
   it('root exist', function () {
     var foo = 'foo'
       , bar = undefined;