This study compared more than 1,000 high school students who participated in service-learning programs with those who did not participate in schools matched for similar demographics and student achievement profiles. The intention was to estimate the effects of service-learning compared to more traditional ways of teaching similar subject areas. The outcomes measured ranged from civic knowledge, behaviors, and dispositions to school engagement factors, such as attachment to school and enjoyment of coursework, that generally predict academic success. Students came from sites in the southeast, north central, and western parts of the United States. More than half of the students in the sample were Latino/Hispanic. Although service-learning students scored higher than comparison students on several outcomes, most of the differences were not statistically significant. Service-learning students were significantly more likely to say that they intended to vote and that they enjoyed school. There were substantial differences in outcomes among the various service-learning programs in the study. The study suggests that service-learning is effective when it is implemented well, but it is no more effective than conventional social studies classes when the conditions are not optimal. In particular: (1) Student outcomes improved when service-learning programs lasted longer, although year-long programs often had slightly less benefit than semester-long programs; (2) Teacher characteristics were related to outcomes--Number of years of teaching experience was significantly related to some student outcomes (valuing school, enjoying math and science, civic skills, and civic dispositions). Longer experience using service-learning was associated with higher civic knowledge, civic dispositions, and efficacy scores; (3) The type of service project was related to the outcomes. Students who engaged in direct service (e.g., tutoring or visiting seniors) were most attached to their communities--Students who engaged in indirect service (e.g., fundraising or research) showed the highest levels of academic engagement. Students who engaged in political or civic action (e.g., circulating a petition or organizing a community forum) scored highest on civic knowledge and civic dispositions; and (4) The literature has identified a set of best practices or "Essential Elements" of service-learning. The study found that some of these elements were related to positive student outcomes, but some were not. who did not use service-learning were almost as likely as those who did to use "active" instructional techniques. Thus, based on this study, it does not appear that service-learning competes against passive, lecture-style classes. Instead, it competes against mixed forms of instruction that include student projects, presentations, debates, and field trips. The study found that the use of active teaching techniques was most beneficial for student outcomes, and service-learning conferred a small additional benefit over other active pedagogies. (Contains 41 exhibits.) [This working paper was produced by the Center for Information & Research on Civic Learning & Engagement (CIRCLE).]