With the widespread emergence of required community-service programs comes a new opportunity to examine the effects of requirements on future behavioral intentions. To investigate the consequences of such "mandatory volunteerism" programs, we followed students who were required to volunteer in order to graduate from college. Results demonstrated that stronger perceptions of external control eliminated an otherwise positive relation between prior volunteer experience and future intentions to volunteer. A second study experimentally compared mandates and choices to serve and included a premeasured assessment of whether students felt external control was necessary to get them to volunteer. After being required or choosing to serve, students reported their future intentions. Students who initially felt it unlikely that they would freely volunteer had significantly lower intentions after being required to serve than after being given a choice. Those who initially felt more likely to freely volunteer were relatively unaffected by a mandate to serve as compared with a choice. Theoretical and practical implications for understanding the effects of requirements and constraints on intentions and behavior are discussed.