The first release of UII is User Interface Integration for Microsoft Dynamics CRM 4.0, which is denoted as UII R1.

The second release of UII is User Interface Integration for Microsoft Dynamics CRM 2011, which is denoted as UII R2.

The third release of UII is User Interface Integration for Microsoft Dynamics CRM 2013 and Microsoft Dynamics CRM Online Fall '13, which is denoted as UII R3.