Active Directory authentication is critical for enabling enterprise-ready applications and cloud services. Learn how apps installed on a user’s devices can use Windows Active Directory to authenticate the user to cloud hosted services, enabling single sign-on with both Windows Azure Active Directory as well Windows Server Active Directory accounts. The session is developer-focused, showing a walkthrough of developing a line-of-business application using the Active Directory Authentication Library, as well as demonstrating how to make your apps available as Software as a Service to multiple organizations using Active Directory. Learn the details of how OAuth 2.0 is used to secure the REST web service calls, going deep enough to understand how this simple protocol can be easily implemented on a variety of device platforms. We also look at the controls available to the Windows Azure Active Directory tenant administrator for controlling app authorization to services.