If you use ASP.NET roles, use the ASP.NET Role Provider
Jason Taylor, Prashant Bansode, Carlos Farre, Madhu Sundararajan, Steve Gregersen
If you are already using the ASP.NET roles, you can leverage pre-existing ASP.NET roles to use in your WCF service, using the Role Manager. The Role information can be stored in SQL Server, or roles can be windows groups when using Windows Authentication or
in an Authorization Manager (AzMan) policy store in ADAM.
The role manager feature supports creation and managing the roles and automatically performs role lookup for the authenticated users. You can use both declarative as well as imperative authorization using the role manager.