Based upon developmental models of disruptive behavior problems, this study examined the hypothesis that the nature of a child's externalizing problems at home may be important in predicting the probability of and nature of school adjustment problems at school entry. Parent ratings were collected for a sample of 631 behaviorally disruptive children using the Child Behavior Checklist. Confirmatory factor analyses revealed differentiated ratings of oppositional, aggressive, and hyperactive/inattentive behaviors at home. Teacher and peer nominations assessed school adjustment at the end of first grade. As expected from a developmental perspective, aggressive behaviors indicated more severe dysfunction and were more likely to generalize to the school setting than were oppositional behaviors. Hyperactive/inattentive behaviors at home led to more classroom disruption than did aggressive or oppositional behaviors. Co-occurring patterns of oppositional/aggressive and hyperactive/inattentive behaviors were more common than were single-problem patterns, and were associated with broad dysfunction in the social and classroom contexts. The results were interpreted within a developmental framework, in which oppositional, aggressive, and hyperactive/inattentive behaviors may reflect distinct (as well as shared) developmental processes that have implications for the home-to-school generalization of behavior problems and subsequent school adjustment.