This longitudinal study examined factors that contribute to the persistence of underrepresented racial minority (URM) undergraduates in STEM fields. The primary source of data came from the Cooperative Institutional Research Program's 2004 The Freshman Survey (TFS) and 2008 College Senior Survey (CSS). The sample included 3,670 students at 217 institutions who indicated on the TFS that they intended to major in a STEM field, 1,634 of whom were underrepresented minority (URM) students. Findings indicate that Black and Latino undergraduates were significantly less likely to persist in STEM majors than were their White and Asian American counterparts. Background characteristics and college experiences moderated this race effect, suggesting both that pre‐college factors may explain some of the observed racial disparities and that individual institutions can take more concrete actions to improve science achievement. Findings from the follow‐up analysis of the sample of URMs suggest that institutions can improve URM STEM persistence by increasing the likelihood that those students will engage in key academic experiences: studying frequently with others, participating in undergraduate research, and involvement in academic clubs or organizations. © 2014 Wiley Periodicals, Inc. J Res Sci Teach 51: 555–580, 2014