Much recent research on sexual minorities has used couples-based samples, which—by construction—provide no information on nonpartnered individuals. We present the first systematic empirical analysis of partnership and cohabitation among self-identified gay men and lesbians using two independent, large, population-wwbased data sources from California. These data indicate that 37%–46% of gay men and 51%–62% of lesbians aged 18–59 are in cohabiting partnerships (compared with 62% of heterosexual individuals in coresidential unions at comparable ages). Unlike previous research, we find that white and highly educated gay men and lesbians are more likely to be partnered, and we confirm that same-sex cohabiting partners in our data have demographic characteristics that are similar to California same-sex couples from Census 2000. We also present the first detailed analysis of officially registered domestic partnerships in California. We find that almost half of partnered lesbians are officially registered with the local or state government, while less than a quarter of partnered gay men are officially registered. We conclude with implications of our findings for couples-based research on gay men and lesbians, as well as recommendations for survey data collection.