Programmatically obtain a list of Active Directory groups that an individual is a member of

Here is some sample code that will allow you to obtain a complete list of all of the Active Director groups that a specified user is a member of:

public void GetGroupsUserIsMemberOf(string sAMAccountName)
{
    try
    {
        using (DirectoryEntry dirEntry = new DirectoryEntry())
        {
            dirEntry.Path = "LDAP://OU=OUName,DC=DCName,DC=org";
            dirEntry.AuthenticationType = AuthenticationTypes.Secure;

            using (DirectorySearcher dirSearch = new DirectorySearcher(dirEntry))
            {
                dirSearch.Filter = string.Format("(&(objectCategory=person)(objectClass=user)(SAMAccountName={0}))", sAMAccountName);
                dirSearch.PropertiesToLoad.Add("memberOf");
                SearchResult result = dirSearch.FindOne();
                if (result != null)
                {
                    int propCount = result.Properties["memberOf"].Count;
                    for (int i = 0; i <= propCount - 1; i++)
                    {
                        // Clean up the name of the group for display purposes
                        char[] delim = new char[] { ',', '\\' };
                        string groupName = result.Properties["memberOf"][i].ToString().Split(delim).First().Replace("CN=", string.Empty);
                        Console.WriteLine(string.Format("Group# {0}: {1}", i+1, groupName);
                    }
                }
            }
        }
    }
}