This project aims to serve national interest by establishing practices to improve the retention of Black, Indigenous, and Latine (BIL) STEM majors during the critical transition from beginning to advanced work. Positionality, which supports culturally relevant pedagogy, is a reflective process in which one evaluates how one's values, views, social position, and power shape one's identity and access to and interactions with society. This project will employ several interventions (including courses, peer mentoring, and professional development) in which students explore positionality to connect their race/ethnicity, culture, and background with STEM disciplines and increase their STEM identity and sense of belonging. The students will explore positionality in a developmental, stepwise curriculum as it relates to themselves, their peers, other STEM professionals, and their STEM fields. The activities will motivate the students to learn and to persist in STEM, particularly during the first two years of STEM education, where attrition rates are highest. New knowledge developed from the project will contribute to the evidence base regarding culturally responsive interventions to develop STEM belonging and identity and to increase the retention of BIL students in STEM. Increasing the racial and ethnic diversity of STEM graduates in the United States has been identified as a key strategy to expand the STEM workforce and maintain the nation's global leadership in STEM.<br/><br/>The project will engage two cohorts of twenty BIL STEM majors during their first two years at a predominantly white institution. The students will reflect on positionality in a developmental curriculum that begins with the exploration of their own positionality, continues with examining positionality of STEM peers and professionals, and concludes with application to their own STEM professional development. In this process, the students will participate as a cohort in a three-course sequence, virtual summer experience, peer mentoring, preparation for professional experiences, and travel to culturally relevant STEM conferences. Through faculty development in pedagogy related to positionality, the project team hopes to extend the impact of the program to the nearly 1,500 students enrolled in introductory STEM courses. A longitudinal mixed-methods research study will investigate the mechanisms connecting positionality to BIL students' identity, belonging, and retention in STEM. Participants will engage in surveys, focus groups, and interviews three times over the course of the study. Data will be collected upon enrollment in the program, after completion of the first course, and at the completion of the program. Iterative project evaluation will take place, with feedback incorporated across the cohorts. The findings will help build the knowledge base for culturally responsive interventions early in a student's academic trajectory, promoting the improvement of STEM identity and belongingness and, ultimately, the retention of STEM students from underrepresented backgrounds. Other institutions will be able to adapt the interventions, and the interventions should be scalable to other marginalized groups of students (women, low-income, first-generation, disabled, LGBTQ+, and intersectional identities).<br/><br/>The NSF IUSE: EDU Program supports research and development projects to improve the effectiveness of STEM education for all students. Through the Engaged Student Learning track, the program supports the creation, exploration, and implementation of promising practices and tools.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.