In this review, we examine the oft-made claim that peer-relationship difficulties in childhood predict serious adjustment problems in later life. The article begins with a framework for conceptualizing and assessing children's peer difficulties and with a discussion of conceptual and methodological issues in longitudinal risk research. Following this, three indexes of problematic peer relationships (acceptance, aggressiveness, and shyness/withdrawal) are evaluated as predictors of three later outcomes (dropping out of school, criminality, and psychcpathology). The relation between peer difficulties and later maladjustment is examined in terms of both the consistency and strength of prediction. A review and analysis of the literature indicates general support for the hypothesis that children with poor peer adjustment are at risk for later life difficulties. Support is clearest for the outcomes of dropping out and criminality. It is also clearest for low acceptance and aggressiveness as predictors, whereas a link between shyness/withdrawal and later maladjustment has not yet been adequately tested. The article concludes with a critical discussion of the implicit models that have guided past research in this area and a set of recommendations for the next generation of research on the risk hypothesis.There are striking individual differences in the extent to which children are accepted by their peers. In the extreme, some children are well regarded by all and enjoy many friendships, whereas others are nearly universally disliked and have no friends. In this review, we consider the implication of variability in acceptance or in acceptance-relevant behavior (aggression and shyness/withdrawal) for children's subsequent personal adjustment in three domains: dropping out of school, juvenile and adult criminality, and adult psychopathology. Our goal is to evaluate the empirical support for the premise that poorly accepted children stand a greater chance than others of developing later life difficulties and, therefore, should be considered a group of children at risk. This premise is widespread in the social development literature. Indeed, it serves as the explicit rationale for attempts to delineate the social skills that ensure adequate peer