DescriptionThe psychological study of race has experienced a recent surge of interest in the lay beliefs that individuals hold about the nature of race. In the following paper, I propose a moderated race concepts model, where the effect of race concepts on race-relevant attitudes is moderated by race concept certainty (RCC)—the extent to which an individual is certain in their beliefs about race. Drawing on the attitude strength literature, I develop a measure of RCC in three studies. In the first set of studies, I use a diverse online sample to reduce the number of items (from 25 to 8; Study 1a) and use an undergraduate sample to explore the factor structure of the reduced scale (2 factors; Study 1b). Results from Study 2 confirm that the eight item measure of RCC has 2 factors: Personal and epistemic certainty. Contrary to hypotheses, concept certainty did not moderate the effect of race concepts on measures of racial attitudes (Study 3). However, concept certainty was reliably associated with biological (positively) and social-constructivist (negatively) race concepts across all but the final study. I review the limitations of the correlational test of the expected moderation effect and possible methods for independently manipulating the components of RCC. I discuss the possibility that the RCC scale assesses a factor without parallels to attitude strength.