diff --git a/lib/uaa/token_issuer.rb b/lib/uaa/token_issuer.rb
index 99f294a..54c3656 100644
--- a/lib/uaa/token_issuer.rb
+++ b/lib/uaa/token_issuer.rb
@@ -75,6 +75,8 @@ def request_token(params)
     if scope = Util.arglist(params.delete(:scope))
       params[:scope] = Util.strlist(scope)
     end
+    client_assertion = params[:client_assertion]
+    params.delete(:client_assertion)
     headers = {'content-type' => FORM_UTF8, 'accept' => JSON_UTF8}
     if @client_auth_method == 'client_secret_basic' && @client_secret && @client_id
       if @basic_auth
@@ -88,6 +90,10 @@ def request_token(params)
       params[:client_secret] = @client_secret
     elsif @client_id && params[:code_verifier]
       params[:client_id] = @client_id
+    elsif client_assertion && @client_id && @client_secret.nil?
+      params[:client_id] = @client_id
+      params[:client_assertion] = client_assertion
+      params[:client_assertion_type] = 'urn:ietf:params:oauth:client-assertion-type:jwt-bearer'
     else
       headers['X-CF-ENCODED-CREDENTIALS'] = 'true'
       headers['authorization'] = Http.basic_auth(CGI.escape(@client_id || ''), CGI.escape(@client_secret || ''))
@@ -129,6 +135,7 @@ def jkey(k) @key_style ? k : k.to_s end
   #   * +:symbolize_keys+, if true, returned hash keys are symbols.
   def initialize(target, client_id, client_secret = nil, options = {})
     @target, @client_id, @client_secret = target, client_id, client_secret
+    @client_assertion = options[:client_assertion] || nil
     @token_target = options[:token_target] || target
     @key_style = options[:symbolize_keys] ? :sym : nil
     @basic_auth = options[:basic_auth] == true ? true : false
@@ -310,8 +317,8 @@ def owner_password_credentials_grant(credentials)
   # Uses the instance client credentials to get a token with a client
   # credentials grant. See http://tools.ietf.org/html/rfc6749#section-4.4
   # @return [TokenInfo]
-  def client_credentials_grant(scope = nil)
-    request_token(grant_type: 'client_credentials', scope: scope)
+  def client_credentials_grant(scope = nil, client_assertion = nil)
+    request_token(grant_type: 'client_credentials', scope: scope, client_assertion: client_assertion)
   end
 
   # Uses the instance client credentials and the given +refresh_token+ to get
diff --git a/spec/token_issuer_spec.rb b/spec/token_issuer_spec.rb
index 2a37aa4..deeb19b 100644
--- a/spec/token_issuer_spec.rb
+++ b/spec/token_issuer_spec.rb
@@ -345,6 +345,37 @@ module CF::UAA
     end
   end
 
+  context 'with client_assertion using client credentials grant' do
+    let(:client_id) { 'test_client' }
+    let(:client_secret) { nil }
+
+    it 'use client_secret_post in authorization code and expect client_id and secret in body' do
+      subject.set_request_handler do |url, method, body, headers|
+        headers['content-type'].should =~ /application\/x-www-form-urlencoded/
+        headers['accept'].should =~ /application\/json/
+        headers['X-CF-ENCODED-CREDENTIALS'].should_not
+        headers['authorization'].should_not
+        params = Util.decode_form(body)
+        params['grant_type'].should == 'client_credentials'
+        params['client_id'].should == 'test_client'
+        params['client_assertion'].should == 'any-jwt-token'
+        params['client_assertion_type'].should == 'urn:ietf:params:oauth:client-assertion-type:jwt-bearer'
+        params['client_secret'].should_not
+        url.should match 'http://test.uaa.target/oauth/token'
+        method.should == :post
+        reply = {access_token: 'test_access_token', token_type: 'BEARER',
+                 scope: 'logs.read', expires_in: 98765}
+        [200, Util.json(reply), {'content-type' => 'application/json'}]
+      end
+      token = subject.client_credentials_grant('logs.read', 'any-jwt-token')
+      token.should be_an_instance_of TokenInfo
+      token.info['access_token'].should == 'test_access_token'
+      token.info['token_type'].should =~ /^bearer$/i
+      token.info['scope'].should == 'logs.read'
+      token.info['expires_in'].should == 98765
+    end
+  end
+
   context 'pkce with own code verifier' do
     let(:options) { {basic_auth: false, code_verifier: 'umoq1e_4XMYXvfHlaO9mSlSI17OKfxnwfR5ZD-oYreFxyn8yQZ-ZHPZfUZ4n3WjY_tkOB_MAisSy4ddqsa6aoTU5ZOcX4ps3de933PczYlC8pZpKL8EQWaDZOnpOyB2W'} }