This study examines the success of undergraduate students in computer science supplementary courses offered by a non-profit organization in partnership with colleges and universities across the U.S. Using a novel dataset from the nonprofit organization, we present one of the first descriptive overviews of students enrolled in supplemental computer science programs. Moreover, we conduct a survival analysis finding that racial and gender disparities in traditional computer science programs exist in these supplemental courses. However, the study finds that when supplemental courses are taken for credit, students are much more likely to complete the course, offering an important insight into program design and student motivation.