Hi, This is my first post here and after much looking around I have come here with my question. Will really appreciate a fast response. I am faced with a problem to validate user credentials of the currently logged on user against a group in Windows. The user membership to a group can be through other groups also ie nested membership. Eg. User U is a part of group G1. Group G1 is a part of another group G2. The requirement is that when the user is validated against group G2, the validations should succeed. The user can be a local or AD user but the group will always be a local group ( or domain local group if created directly on a DC). I have tried using WindowsPrincipal.IsInRole() method, but it seems to be checking only for direct membership to a group. I also tried UserPrincipal.GetAuthorizationGroups() for the current user, but it also doesnt seem to be doing recursive search. I am posting a code snippet of the working code below, but this code is taking much more than acceptable time. bool CheckUserPermissions(string groupName) { WindowsIdentity currentUserIdentity = System.Security.Principal.WindowsIdentity.GetCurrent(); bool found = false; PrincipalContext context= new PrincipalContext(ContextType.Machine); GroupPrincipal group = GroupPrincipal.FindByIdentity(context, IdentityType.Name, groupName); if (group!= null) { foreach (Principal p in group.GetMembers(true)) { if (p.Sid == currentUserIdentity.User) { found = true; break; } } group.Dispose(); } return found; }