Research has frequently remarked on the conceptual overlap of racial versus ethnic categories at the macro-level, as well as on individual-level inconsistencies across multiple dimensions of race. Less research has focused on the interpersonal negotiation of racial self-classification and identity claims-making, or on the norms that govern racial appraisal. This study uses a case at the boundaries of the Hispanic category to ask: what norms of self-classification and social appraisal do interlocuters draw on in their interpretation of ethnic categories? I answer this question using a unique dataset of posts from a college admissions forum, in which prospective applicants ask, “Am I Hispanic?” Findings reveal that ancestry forms the most rigid boundary, though interlocuters debate whether ancestry is biological or cultural. Cultural identity is also necessary, though more loosely defined. Specific, noninstitutionalized traits, such as phenotype, language, and surname, are considered neither necessary nor sufficient. Findings highlight the enduring primacy of ancestry and the importance of social appraisal in the college application context.