Previous research suggests that adults' essentialist beliefs depend on their own social-group membership. However, these studies have examined the effects of one social-group membership at a time (e.g., the influence of race on essentialism of race), even though all individuals belong to multiple social groups. It is therefore unclear whether membership in one social category (e.g., ethnicity) predicts essentialism of another category (e.g., SES). To address this question, the present study simultaneously explored the relationship between individuals' racial and ethnic background and subjective SES and their essentialism of ethnicity and SES. Results showed that participants' racial and ethnic background predicted their essentialist beliefs about ethnicity, but their subjective SES did not. In contrast, participants' subjective SES and ethnicity interacted to predict their essentialist beliefs about SES: for non-Hispanic White individuals, higher subjective SES predicted stronger essentialist beliefs about SES across multiple dimensions of essentialism, but no such pattern emerged for members of racial and ethnic minority groups. These findings suggest that adults' essentialist beliefs are influenced by a complex interplay of their multiple social-group memberships.