It depends on the group you are in. Typically for a group where you are showing up to a facility, you will get paid at the end of a session. For something like a telephone or web-interview, it is within 4 to 6 weeks upon completion of the study. (You typically get your check within 2 to 3 weeks, but we want to cover ourselves because sometimes these studies go on for a weeks and all the checks are sent when everyone has completed the study)