The authors describe an innovative summer enrichment program based on a cascading mentorship model to transfer knowledge and skills from faculty to medical students to undergraduate students and finally to high school students. The program was designed to give high school students a glimpse of life in medical school and enhance the teaching and leadership skills of underrepresented undergraduate and medical students. Started in 2010 with 30 high school students and 9 college and medical student coaches, the University of California, Irvine, School of Medicine Summer Premed Program expanded rapidly over the next two summers and enrolled a total of 253 high school students, 48 college students, and 12 medical students. The college and medical student coaches, the majority of whom were underrepresented in medicine (URIM), reported that the program enhanced their teaching and leadership skills and self-confidence, motivated them toward careers in academic medicine, and raised their awareness about the importance of cultural diversity. The authors present the details of this interactive, structured program and describe how URIM student empowerment, near-peer teaching, science socialization, and support from the institution's leadership and faculty members provided a climate that fostered belonging, a sense of personal transformation, and professional development among students from different levels of education and diverse backgrounds. Long-term follow-up of the participants' career choices is needed.