This qualitative study explored how critical incidents shape multiracial students' understanding of race and identity at predominantly White institutions. Participants included 14 multiracial undergraduate students from two institutions in the Midwest. Four categories of critical incidents were identified from the data: (a) confronting race and racism, (b) responding to external definitions, (c) defending legitimacy, and (d) affirming racial identity. The incidents took many forms and occurred in many contexts. The majority of incidents involved interactions with other students, underscoring the influence of peers. The study also suggests implications for higher education practice and research. (Contains 2 tables.)