This study applied self-determination theory to youth purpose development among Korean college students. It examined the effects of students' intrinsic motivation for volunteering and informative feedback from significant others on three dimensions of life purpose: confidence in purpose, commitment to purpose and social contribution. The study also tested whether informative feedback influenced the relationship of intrinsic motivation and life purpose development. Participants were 110 Korean college students taking a one-semester service-learning class. The results showed that informative feedback positively affected commitment to purpose and social contribution, especially for students who had low intrinsic motivation. Intrinsic motivation and feedback both positively predicted students' confidence in purpose. To positively influence students' life purpose development, these results suggest the importance of providing college students with intrinsically motivated experiences plus informative feedback that supports their competence during service work.