Disruptive behavior may be associated with poor academic achievement due to covariance with attention problems and low IQ. Evidence is based on clinical samples and on associations between problem behaviors in young children and later achievement difficulties. The contemporaneous relations and their genetic and environmental influences have not been understood. Using the population-based Minnesota Twin Family Study, the authors observed this pattern of associations in 11-year-olds. About 75% of variance in latent inattention, ability, behavior, and school grades variables was genetic. Genetic influences on inattention and grades and on ability and grades were highly overlapping. Those on disruptive behavior were less closely related.