Using data from the 2002 National Survey of America's Families, the authors find that the majority of the gaps in poverty, low-income status, and food insecurity between children living in cohabiting and married couple families is accounted for by differences in characteristics such as parental education, age, and the number of hours worked. The benefits of marriage and unmeasurable characteristics, such as attitudes towards commitment, account for the rest of the difference. The authors conclude that successful marriage promotion efforts aimed at cohabiting parents could improve the outcomes for their children, but only to a limited extent.