A quasi-experimental study was conducted to investigate the effectiveness of using a service learning (SL) method on influencing introductory engineering students' motivation and ABET program outcomes, compared to the effectiveness of using a conventional, non-service-learning (NSL) method. The sample used in the study was 214 students enrolled in an Introduction to Engineering course at a medium-size university in the northwestern region of the U.S. during the fall semester of 2009 and the spring semester of 2010. Sixty-nine students completed SL projects while 145 students completed NSL projects. Both SL and NSL projects were team-based. Using the ARCS model as a framework, students' motivation was measured on attention (interest), relevance, confidence in engineering knowledge, confidence in collaborative learning, and satisfaction. Students' self-assessed engineering abilities were measured on the "a through k" ABET program outcomes. Results showed that the SL method was significantly more effective than the NSL method in terms of positively influencing students' interests, recognition of relevance, and satisfaction in learning and their self-assessed engineering abilities in three out of 11 ABET program outcomes, c, e, and k. Interpretation of the results, application of the results to the course redesign, and recommendations for other engineering educators are provided. (Contains 6 tables and 8 figures.)