Relatively little is known about differences in how married and cohabiting couples share their economic resources. Using the 2001 panel of the Survey of Income and Program Participation (SIPP), this study compares the extent of household expense sharing among married and cohabiting couples focusing on gender specialization differences between married and cohabiting couples. Current debates question the relative differences between married and cohabiting relationships. Multinomial logistic analyses suggest that relative resources indeed do much to explain who pays the majority of household expenses, but also find support for differences across family structure. Married couples are more likely than cohabiting couples to have a single male provider compared to other sharing arrangements. Households with a child not biologically related to one partner are more likely to have a female provider, while households with biological children are more likely to have a male provider.