This Project Grant from the National Science Foundation's STEM Education program, formerly known as Education and Human Resources (CFDA 47.076), provides $499,947 to San Francisco State University to implement and evaluate a peer mentor support system for undergraduate computer science students from August 1, 2022 to July 31, 2025. The project aims to build an inclusive and sustainable learning community through peer mentoring to enhance the quality of computer science education and increase retention and graduation rates of underrepresented students. Specifically, the university will recruit and train diverse peer mentors in equitable and inclusive teaching techniques and establish an affirming mentoring program. This is intended to directly benefit approximately 800 undergraduate computer science students annually, including peer mentors, by addressing deficiencies in educational resources and sense of belonging among marginalized groups in the field. The grant will also support research on the impact of peer mentoring on mentees' identity, belonging and retention, as well as benefits to mentors such as pedagogical development. Results will be disseminated through conferences and publications to contribute new knowledge for supporting underrepresented students in STEM.