Is the _ISADMIN variable supposed to work with domain accounts? My work (domain) account has admin rights on my local workstation but not (obviously) on the domain. With the domain account _ISADMIN always has the value 0, even if I can do local administrative tasks like the change the time, open device manager, install programs etc. With a local (workstation) admin account I have created _ISADMIN has the value 1 as expected. More info: My work PC is using Windows XP SP3 so it's not a Vista UAC issue. The local Administrators group also contains my domain account.