The overall goal of the present study is to understand the processes that may place younger siblings of delinquent adolescents at risk for conduct problems themselves, and consequently to contribute to efforts to prevent delinquency in children from high-risk families. Objectives include the understanding of aspects of children's relationships with delinquent older siblings, the identification of learning processes that may occur within the context of the sibling relationship, and an examination of the relative predictive power of the sibling relationship for predicting younger sibling conduct problems as compared to parental monitoring, coervice discipline, parental rejection of the child, parental criminality, and marital discord. Sixty-five families with an adjudicated delinquent adolescent and at least one child who is younger than the adolescent and in third grand or higher will participate in the study. Aspects of the sibling relationship, processes of learning problem behavior, and family factors mentioned above will be assessed in individual interviews with each participating child and parent. It is expected that positive and negative qualities of the sibling relationship, perceptions of the social status of the delinquent adolescent, and perceptions of the consequences to the delinquent adolescent for his or her problematic behavior will be associated with the learning of conduct problem behavior. In addition, it is expected that four types of learning, including direct influence, modeling and emulation, coercion, and introduction into a deviant peer group, will be associated with conduct problem behavior in the younger sibling. Finally, it is expected that these aspects of the sibling relationship will explain additional variance in younger siblings' conduct problems after accounting for the variance explained by the other family factors mentioned above.