Two studies tested the hypothesis that perceivers' prejudice and targets' facial expressions bias race categorization in stereotypic directions. Specifically, we hypothesized that racial prejudice would be more strongly associated with a tendency to categorize hostile (but not happy) racially ambiguous faces as African American. We obtained support for this hypothesis using both a speeded dichotomous categorization task (Studies 1 and 2) and a rating-scale task (Study 2). Implicit prejudice (but not explicit prejudice) was related to increased sensitivity to the targets' facial expressions, regardless of whether prejudice was measured after (Study 1) or before (Study 2) the race categorizations were made.