We analyze the effects of family capital on child behavior problems in the United States and Great Britain by comparing a longitudinal survey sample of 5- to 13-year-old children from the 1994 National Longitudinal Survey of Youth (N = 3,864) with a similar sample of children from the 1991 National Child Development Study "British Child" (N = 1,430). Findings suggest that in both societies, male children, those with health problems, and those whose mothers are divorced are at increased risk for behavior problems, while those with stronger home environments are at reduced risk. Family structure effects are more pervasive in Great Britain than in the United States, although some of these findings are a function of our racially diverse U.S. sample. We conclude that parents are important in both societies in promoting child social adjustment, and evidence that the more developed welfare state in Great Britain may substitute for capital at home is weak. (Contains 3 tables and 6 notes.)