This study evaluates the effectiveness of the UCSF Summer Student Research Program (SSRP) in enhancing research-related skills, academic outcomes, and post-baccalaureate aspirations of underrepresented minority (URM) and non-URM undergraduate students in biomedical sciences and STEM fields. The SSRP, spanning 9 weeks, provides immersive research experiences, structured mentorship, trainings, seminars, and STEM education. Pre- and post-program survey data from eight cohorts (N = 315) were analyzed using paired-sample t-tests, MANOVA, and content analysis. Results demonstrate significant gains in critical thinking skills, research abilities, science identity, applied science skills, and readiness for a research career. Notably, participants exhibited improvements in understanding the research process, scientific thinking, science writing, and problem-solving. URM and non-URM students experienced similar gains, highlighting the program's inclusivity. The SSRP also positively influenced students' postgraduate aspirations. Some participants expressed heightened interest in pursuing Master of Arts, Ph.D., and M.D. degrees, indicating increased clarity and motivation towards advanced education and research careers. Furthermore, 87% of participants expressed a high likelihood of engaging in future research endeavors, underscoring the program's sustained impact on research interest. This study underscores the transformative potential of a well-structured, intensive summer research program in significantly enhancing academic outcomes for URM and non-URM students alike. These findings align with the persistence framework, emphasizing the importance of early research experiences, active learning, and learning communities in fostering student success. The SSRP's effectiveness in improving research skills and post-baccalaureate aspirations suggests its potential in diversifying the STEM fields, biomedical sciences and health-related professions.