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