This High Impact Practices (HIPS) contribute to higher retention and graduation rates. HIPS are effective for racial and ethnic minorities in particular, who disproportionately experience high and persistent levels of postsecondary attrition. Little is known about the mechanism by which HIPS promote retention. Based on a random survey of 268 undergraduate students, we conclude that HIPS correlate with "engagement", defined as the alignment of student and institution (identified in the present study by behavioral and cognitive measures) and posit that this is the likely mechanism by which HIPS affect retention. Moreover, exposure to HIPS and the relationship between HIPS and engagement varies based on race/ethnicity. HIPS that have an effect on engagement across racial categories are service learning, undergraduate research, group assignments, learning communities, sequence courses, and, especially, having a close faculty mentor. In addition to these factors, diversity-related course content is especially effective for racial/ethnic minority engagement. Implications for educators and policy-makers are elucidated.