Despite the importance of preparing socially responsible graduates in science, technology, engineering, and mathematics (STEM) to address the current state of poverty and inequality, very few studies in higher education have examined the development of STEM students' outcomes critical to promoting a more equitable society, typically focusing on the impact of one program or course. To address this gap in the literature, this study used frameworks of undergraduate socialization as well as social justice perspectives in STEM education to examine the undergraduate experiences and institutional contexts that predict STEM bachelor's degree recipients' development of two democratic educational outcomes seven years after college entry: social agency and values toward conducting research that will have a meaningful impact on underserved communities. The study utilized multilevel modeling on a national longitudinal sample of 6341 STEM bachelor's degree recipients across 271 institutions. Longitudinal student data from the 2004 Cooperative Institutional Research Program's (CIRP) Freshman Survey and 2011 Post-Baccalaureate Survey were merged with institutional data from the Integrated Postsecondary Educational Data System and CIRP Faculty Surveys. Various undergraduate socialization experiences and institutional contexts were found to predict STEM bachelor's degree recipients' democratic educational outcomes, including academic majors, participation in student organizations and research, experiences with faculty, and peer and STEM faculty normative contexts. Implications of the findings for research, policy, and practice are discussed.