Many hold that ordinary race-thinking in the USA is committed to the 'one-drop rule', that race is ordinarily represented in terms of essences, and that race is ordinarily represented as a biological (phenotype- and/or ancestry-based, non-social) kind. This study investigated the extent to which ordinary race-thinking subscribes to these commitments. It also investigated the relationship between different conceptions of race and racial attitudes. Participants included 449 USA adults who completed an Internet survey. Unlike previous research, conceptions of race were assessed using concrete vignettes. Results indicate widespread rejection of the one-drop rule, as well as the use of a complex combination of ancestral, phenotypic, and social (and, therefore, non-essentialist) criteria for racial classification. No relationship was found between racial attitudes and essentialism, the one-drop rule, or social race-thinking; however, ancestry-based and phenotype-based classification criteria were associated with racial attitudes. These results suggest a complicated relationship between conceptions of race and racial attitudes.