One of the major selling points of service-learning courses is their potential to mutually benefit communities, universities, and students. Although a great deal of research reports numerous pedagogical and personal benefits for students--from improved grades and increased civic engagement to increased understanding and appreciation of diversity--there is relatively little research on the impact of service learning on the community. To understand when and how service-learning courses benefit the community, we conducted in-depth interviews with representatives of local community-based organizations that have worked with service learners. We report on the primary benefits and costs associated with service-learning courses. We identify three types of obstacles to successful service-learning courses: issues related to student conduct, poor fit between course and organizational objectives, and lack of communication between instructors and organizations. We develop practical guidelines for addressing these obstacles and for ensuring that service learning fulfills teaching and learning goals and provides valuable service to community-based organizations. (Contains 1 table and 7 footnotes.)