This study uses Fragile Families data (N = 2,160) to assess health differences at age 5 for children born to cohabiting versus married parents. Regression analyses indicate worse health for children born to cohabiting parents, including those whose parents stably cohabited, dissolved their cohabitation, and married, than for children with stably married parents. The findings also suggest that stable cohabitation is no better for child health than cohabitation dissolution. Child health is better among those whose cohabiting parents marry than for those whose parents remain stably cohabiting, which indicates a possible health advantage of parental marriage, even if it occurs after the child's birth. (Contains 1 figure, 5 tables, and 1 note.)