SELECTING with multiple WHERE conditions on same column

Ok, I think I might be overlooking something obvious/simple here... but I need to write a query that returns only records that match multiple criteria on the same column... My table is a very simple linking setup for applying flags to a user ... ID contactid flag flag_type ----------------------------------- 118 99 Volunteer 1 119 99 Uploaded 2 120 100 Via Import 3 121 100 Volunteer 1 122 100 Uploaded 2 etc... in this case you'll see both contact 99 and 100 are flagged as both "Volunteer" and "Uploaded"... What I need to be able to do is return those contactid's ONLY that match multiple criteria entered via a search form...the contactid's have to match ALL chosen flags... in my head the SQL should look something like: SELECT contactid WHERE flag = 'Volunteer' AND flag = 'Uploaded'... but... that returns nothing... What am I doing wrong here?