We examine the impact of the Thompson Scholars Learning Community (TSLC), a comprehensive college transition program serving students with a variety of majors, on students' science, technology, engineering, and math (STEM)-related outcomes. We use an explanatory mixed-methods design, which prioritizes the quantitative analyses and uses qualitative analyses to contextualize and explain our quantitative findings. Overall, participating in TSLC does not make students more likely to declare a STEM major, although we do find a positive effect for students of color. TSLC students earn higher overall GPAs than their scholarship-only peers, and TSLC students majoring in STEM outperform scholarship-only STEM majors in STEM courses. Qualitative analyses suggest these results stem from the student-centered and proactive support the program provides students. Our results suggest that a disciplinarily-agnostic program can support student success in STEM, and may increase equitable representation in STEM fields.