What makes service-learning effective? This article examines key factors influencing student service-learning outcomes in higher education. We studied 2,214 students who had completed a credit-bearing service-learning course in a large public university in Hong Kong. The students were asked to rate the course and pedagogical features, as well as their attainment of the intended learning outcomes of the course. Multiple regressions were then performed to identify and compare the relative contribution of the individual course and pedagogical elements. Results showed that students' attainment of the different service-learning outcomes is influenced to varying degrees by different course and pedagogical elements. Specifically, we found that the most positive outcomes are associated with challenging and meaningful tasks, interest in the subject/project, perceived benefits to people served, preparation for service, and appreciation of the service by the people served. We discuss implications of the findings for theory, practice, and further research.