Bryn Mawr will develop and assess a multifaceted mentorship program to support first-generation and low-income (FGLI) students interested in STEM. This program will improve the early academic and affective experiences of FGLI students through evidence-based supports that employ psychosocial development strategies to foster science identity, self-efficacy, and belonging in STEM. The 3-year project will track two cohorts of FGLI students entering in fall ’21 and fall ’22 through their sophomore year. They will enroll in a “Scientific Thinking” course in their first semester that emphasizes quantitative and computational analysis skills, the scientific inquiry process, and STEM career paths. STEM faculty mentors will receive training in strengths-based advising techniques to support students until they are matched with major advisors at sophomore year-end. Early STEM research experiences and activities will expose students to different pathways to STEM and help them build social networks and cultural capital. By the project’s end, Bryn Mawr will have a mentorship program that addresses the affective needs of FGLI students early in their collegiate STEM studies, improves their academic experience, increases post-graduation retention in STEM, and can be adopted by other institutions.