Increasingly, children are living with cohabiting parents. Prior work on the material well-being of children living in cohabiting families is extended by including the biological relationship of children to adults, examining the racial and ethnic variations, and investigating the multiple indicators of material well-being. We draw on the 1999 National Survey of America's Families ("N"=34,509). Our findings suggest that children can potentially benefit from living with a cohabiting partner whose resources are shared with family members. Although children living with married rather than cohabiting parents fare better in terms of material well-being, this advantage is accounted for by race and ethnic group and parents' education. Marriage appears to provide more material advantages to White children than to Black or Latino children.