diff --git a/README.md b/README.md
index 3e0edda..4534f8b 100644
--- a/README.md
+++ b/README.md
@@ -26,6 +26,7 @@ encoded private key for RSA and ECDSA.
 
 * `algorithm` (default: `HS256`)
 * `expiresInMinutes` or `expiresInSeconds`
+* `notBeforeMinutes` or `notBeforeSeconds`
 * `audience`
 * `subject`
 * `issuer`
@@ -37,7 +38,7 @@ encoded private key for RSA and ECDSA.
 If `payload` is not a buffer or a string, it will be coerced into a string
 using `JSON.stringify`.
 
-If any `expiresInMinutes`, `audience`, `subject`, `issuer`, `jwtid`, `subject` are not provided, there is no default. The jwt generated won't include those properties in the payload.
+If any `expiresInMinutes`, `notBeforeMinutes`, `audience`, `subject`, `issuer`, `jwtid`, `subject` are not provided, there is no default. The jwt generated won't include those properties in the payload.
 
 Additional headers can be provided via the `headers` object.
 
@@ -60,6 +61,7 @@ var token = jwt.sign({ foo: 'bar' }, cert, { algorithm: 'RS256'});
 `options`:
 
 *  `ignoreExpiration`
+*  `ignoreNotBefore`
 *  `audience`
 *  `issuer`
 *  `jwtid`
@@ -81,6 +83,7 @@ encoded public key for RSA and ECDSA.
 * `audience`: if you want to check audience (`aud`), provide a value here
 * `issuer`: if you want to check issuer (`iss`), provide a value here
 * `ignoreExpiration`: if `true` do not validate the expiration of the token.
+* `ignoreNotBefore`: if `true` do not validate the not before of the token.
 * `jwtid`: if you want to check JWT ID (`jti`), provide a value here
 * `subject`: if you want to check subject (`sub`), provide a value here
 
diff --git a/index.js b/index.js
index 945804a..204a165 100644
--- a/index.js
+++ b/index.js
@@ -1,6 +1,7 @@
 var jws = require('jws');
 
 var JsonWebTokenError = module.exports.JsonWebTokenError = require('./lib/JsonWebTokenError');
+var NotBeforeError = module.exports.NotBeforeError = require('./lib/NotBeforeError');
 var TokenExpiredError = module.exports.TokenExpiredError = require('./lib/TokenExpiredError');
 
 module.exports.decode = function (jwt, options) {
@@ -53,6 +54,14 @@ module.exports.sign = function(payload, secretOrPrivateKey, options) {
   if (!options.noTimestamp) {
     payload.iat = payload.iat || timestamp;
   }
+  
+  var notBeforeSeconds = options.notBeforeMinutes ?
+      options.notBeforeMinutes * 60 :
+      options.notBeforeSeconds;
+  
+  if (notBeforeSeconds) {
+      payload.nbf = timestamp + notBeforeSeconds;
+  }
 
   var expiresInSeconds = options.expiresInMinutes ?
       options.expiresInMinutes * 60 :
@@ -167,6 +176,14 @@ module.exports.verify = function(jwtString, secretOrPublicKey, options, callback
   } catch(err) {
     return done(err);
   }
+    
+  if (typeof payload.nbf !== 'undefined' && !options.ignoreNotBefore) {
+    if (typeof payload.nbf !== 'number') {
+      return done(new JsonWebTokenError('invalid nbf value'));
+    }
+    if (payload.nbf >= Math.floor(Date.now() / 1000))
+      return done(new NotBeforeError('jwt not active', new Date(payload.nbf * 1000)));
+  }
 
   if (typeof payload.exp !== 'undefined' && !options.ignoreExpiration) {
     if (typeof payload.exp !== 'number') {
diff --git a/lib/NotBeforeError.js b/lib/NotBeforeError.js
new file mode 100644
index 0000000..7b30084
--- /dev/null
+++ b/lib/NotBeforeError.js
@@ -0,0 +1,13 @@
+var JsonWebTokenError = require('./JsonWebTokenError');
+
+var NotBeforeError = function (message, date) {
+  JsonWebTokenError.call(this, message);
+  this.name = 'NotBeforeError';
+  this.date = date;
+};
+
+NotBeforeError.prototype = Object.create(JsonWebTokenError.prototype);
+
+NotBeforeError.prototype.constructor = NotBeforeError;
+
+module.exports = NotBeforeError;
\ No newline at end of file
diff --git a/test/jwt.rs.tests.js b/test/jwt.rs.tests.js
index 89d231c..18af156 100644
--- a/test/jwt.rs.tests.js
+++ b/test/jwt.rs.tests.js
@@ -88,6 +88,43 @@ describe('RS256', function() {
     });
   });
 
+  describe('when signing a token with not before', function() {
+    var token = jwt.sign({ foo: 'bar' }, priv, { algorithm: 'RS256', notBeforeMinutes: -10 });
+
+    it('should be valid expiration', function(done) {
+      jwt.verify(token, pub, function(err, decoded) {
+        assert.isNotNull(decoded);
+        assert.isNull(err);
+        done();
+      });
+    });
+
+    it('should be invalid', function(done) {
+      // not active token
+      token = jwt.sign({ foo: 'bar' }, priv, { algorithm: 'RS256', notBeforeMinutes: 10 });
+
+      jwt.verify(token, pub, function(err, decoded) {
+        assert.isUndefined(decoded);
+        assert.isNotNull(err);
+        assert.equal(err.name, 'NotBeforeError');
+        assert.instanceOf(err.date, Date);
+        assert.instanceOf(err, jwt.NotBeforeError);
+        done();
+      });
+    });
+
+    it('should NOT be invalid', function(done) {
+      // not active token
+      token = jwt.sign({ foo: 'bar' }, priv, { algorithm: 'RS256', notBeforeMinutes: 10 });
+
+      jwt.verify(token, pub, { ignoreNotBefore: true }, function(err, decoded) {
+        assert.ok(decoded.foo);
+        assert.equal('bar', decoded.foo);
+        done();
+      });
+    });
+  });
+
   describe('when signing a token with audience', function() {
     var token = jwt.sign({ foo: 'bar' }, priv, { algorithm: 'RS256', audience: 'urn:foo' });