The stereotype inoculation model proposes that environments primarily comprised of underrepresented in-group members afford them protection against the inimical effects of stereotypes. We conducted a macrolevel test of this model by examining the conditional effects of university context on students' perceptions of threatening race-science, technology, engineering, math (STEM) stereotypes. Participants were 333 African American undergraduate STEM students attending both a Historically Black College/University (HBCU) and a predominantly White institution (PWI). Results of a hierarchical regression analysis indicated that HBCU students reported significantly lower identity threat than their PWI counterparts when they endorsed both mean and high levels of social identification. Identity threat and social identity were also found to be significant negative and positive predictors of STEM self-efficacy, respectively, after controlling for implicit race-STEM stereotypes and other contextual and intrapersonal factors. Implications for fostering the STEM career development of African American students are discussed.