Using a subsample ( N = 1,365,145) of the 2000 Census 5% Public Use Microdata Sample, the authors investigate explanations for differing poverty chances of cohabiting gay and lesbian, and married and cohabiting heterosexual families. Gay and lesbian couples fare worse than married couples, but better economically than cohabiting heterosexuals. Lesbian and gay families are older and more educated than cohabiting heterosexual families, and these differences explain the largest portion of differences in poverty rates. Greater educational attainment and labor force participation are better explanations than age for differences between married families and their gay and lesbian counterparts. These results add to recent research pointing to variations in the economic circumstances of different family forms. (Contains 3 tables.)