The definition of full-time enrollment varies depending on the session or overlapping sessions. F-1 and J-1 students are required to maintain full-time units throughout their stay in the U.S. If you are an F-1 or J-1 student and at any time (before or after your arrival in the U.S.) you decide to change your class schedule, contact Summer Sessions to make sure your action will not adversely affect your legal status in the U.S.