Previous studies have reported that children from single-parent households fare worse behaviorally than those from two-parent households. Studies examining single-parent households often fail to distinguish between single-mother and single-father households. Further, there are inconsistent findings regarding the effect of family structure on boys and girls. This study examined the relationship between family structures and behavior problems among 515 predominantly ethnic minority children in an urban setting, while taking into account the role of children's gender. Results indicated that children from two-parent families consistently scored lower on measures of externalizing behavior and hyperactivity when compared to children from parent-absent households, but not when compared to those from single-parent households. Moderation analyses revealed significant interactions between family structure and children's gender. Girls in single-mother households scored higher in externalizing behavior and hyperactivity than those in two-parent households. Behavior problems for boys in single-mother households did not differ from those in two-parent households. These findings encourage further research on parenting practices and child's gender within various family structures. (Contains 2 tables, 2 figures and 1 note.)