This study evaluates whether students who participate voluntarily in a service-learning activity achieve higher learning outcomes, measured by grades, than students who voluntarily choose not to participate in service learning. Analysis is based on a study of an introductory urban studies course at a large North American research university over a four-year period. Findings indicate that, overall, students achieve higher grades as a result of participation in service learning, and additionally that females, international students, and students who are enrolled in either the Urban Studies minor program or who are non-Urban Studies students benefit most from optional participation in service learning in terms of grade achievement.