Using the two following commands you can easily retrieve all the groups a user is member of. This command will also take account group membership caused by nested groups. Here’s the first line, it’s a multi-line command that will store all of the groups the users is a member of in the $tokenGroups variable. The groups are represented by their SID.

$tokenGroups = Get-ADUser -SearchScope Base -SearchBase 'CN=thomas,OU=Admin Accounts,DC=contoso,DC=com' `

-LDAPFilter '(objectClass=user)' -Properties tokenGroups | Select-Object `

-ExpandProperty tokenGroups | Select-Object -ExpandProperty Value

In order to easily translate them to their AD AccountName you can use the following command I blogged about earlier (Quick Tip: Resolving an SID to a AccountName)

$groups = $tokengroups | % {((New-Object System.Security.Principal.SecurityIdentifier($_)).Translate( [System.Security.Principal.NTAccount])).Value}

Using the “-SearchSCope Base –SearchBase …” approach seems to be necessary as you cannot simply use Get-ADUser username …