WindowsIdentity.Groups

WindowsIdentity.Groups can be used to display the list of groups that an account belongs to. The following code enumerates the group list and displays both the group name and SID.

WindowsIdentity wi = WindowsIdentity.GetCurrent();
foreach (IdentityReference id in wi.Groups)
{
Console.WriteLine(@" {0}, {1}",
((NTAccount)((SecurityIdentifier)id).Translate(typeof(NTAccount))).Value,
id.Value);
}

However, this property is buggy. So be cautious to use it. I found strange (wrong) behaves.

1. If you list the groups that Network Service or Local Service belongs to, you get two Users groups with the same SID.
2. If you create a local normal user named tmpUser and then remove it from the Users group, then you log out and relog in your system, and then launch your app under the tmpUser account to display the list of groups that it belongs to. You'll find that the Users group still shows up in the list!