While the promise of service-learning for increasing interest and achievement in mathematics and pursuing mathematical careers is apparent, little research has been conducted to show that the promise can be reached. This chapter provides the results of one such study. In one of the sections, the particular service-learning program design will be presented, followed by a description of the study itself, including design, methodology, and results. The chapter ends with a discussion of the factors within service-learning design that appear to be most relevant to increasing student interest in pursuing mathematical careers.