We explore the understudied role of program staff in an out-of-school time (OST) program at a large science museum, which may be especially relevant for supporting underrepresented minority (URM) youth’s interest in science, technology, engineering, or math (STEM) careers. Using a sequential explanatory mixed-method design, we surveyed 167 program alumni on their science attitudes, career interests, and memories about how the program compared to experiences at home, school, and with friends. We followed that with 49 interviews with alumni. Findings show that, while in the program, alumni who