A large literature has documented the influence of family economic resources on child development, yet income's effects in middle childhood have been understudied. Using data from the National Longitudinal Survey of Youth (N = 3,551), the author examined the influence of family income in early and middle childhood on academic skills and behavior problems during middle childhood. Early childhood income had enduring effects on children's behavior problems and academic skills in middle childhood. Middle childhood income did not influence academic skills but did affect the development of behavior problems during middle childhood. Children from low-income households were particularly sensitive to the effects of family income. The quality of home environment during early and middle childhood explained a portion of the effects of income on academic skills and behavior problems.