Several studies have demonstrated that children in stephouseholds do not perform as well in school as children growing up with both biological parents, yet explanations for this relationship remain underdeveloped. Using a nationally representative sample of eighth graders from the 1988 National Education Longitudinal Study, I address two questions: (1) Do parental resources mediate the effect of living in a stephousehold on academic achievement? and (2) Does the sex of the biological parent or child affect these processes? Results indicate that interpersonal, economic, and cultural parental resources explain much of the difference in academic achievement among children from step- and mother/father households. Also, although both boys and girls tend to fare better in mother/stepfather than in father/stepmother households, children do not appear to be more disturbed by the entrance of an opposite-sex than of a same-sex stepparent.