Recently, demographic research on sexual minorities using large-scale surveys has flourished. Yet, there has been little attention paid to whether common survey measures of sexuality – and the use of these measures – capture important racial/ethnic and sex differences, despite evidence suggesting the existence of racial and ethnic differences in how sexuality is both understood and described. This paper focuses on the intersection of race/ethnicity, sex and sexuality, and asks whether the racial/ethnic compositions of populations are sensitive to definitions of non-heterosexual populations, and whether measures of sexuality change over time, racial/ethnic group and sex. Results show that different definitions of non-heterosexual populations influence estimates of racial/ethnic compositions of groups, and that patterns of identification across age cohorts and time also vary by race/ethnicity and sex. Using different theoretical perspectives, the paper concludes with recommendations of how non-heterosexual populations should be conceptualized in future research using large-scale surveys.