Gang membership has long been understood to have a disruptive influence on adolescent development and to contribute disproportionately to the rate of delinquent crime. The nature of the impact, and the long-term effects on individuals, have not been well understood. This book uses longitudinal data to examine the developmental consequences of gang membership, and its longer term influence on the life course. This longitudinal approach is made possible by data from a study of antisocial behavior, The Rochester Youth Development Study, which followed one thousand adolescents through their early adult years. The subjects include delinquents who were gang members and others who were not, allowing the authors to compare motives, patterns of behavior, and recurring problems with caregivers and the law, education, peer relations, and career paths. The findings indicate that multiple developmental deficits lead to gang membership and that membership leads to an increase in delinquency.

This study examines alternative explanations for why gang members are more likely to have higher rates of serious and violent crime than nongang members. Specifically, three models are posited: (a) a selection or “kind of person” model; (b) a social facilitation or “kind of group” model; and (c) an enhancement model that combines aspects of the selection and social facilitation models. Each model has different implications for the rate of delinquency and drug use of gang members before, during, and after membership in a gang. Data from the Rochester Youth Development Study, a panel study that overrepresents adolescents at high risk for serious delinquent behavior and drug use, are used to compare these models. Findings indicate that gang members, as compared to nongang members, did not have higher rates of delinquent behavior or drug use before entering the gang, but once they became members, their rates increased substantially. Moreover, when gang members left the gang their rates of delinquency typically were reduced. These results are interpreted as being supportive of the social facilitation model.

Three theoretical models of the interrelations among associations with delinquent peers, delinquent beliefs, and delinquent behavior are examined. The socialization model views delinquent peers and beliefs as causally prior to delinquent behavior, whereas the selection model hypothesizes that associations with delinquent peers and delinquent beliefs are a result of delinquent behavior. The interactional model combines aspects of both the socialization and the selection models, positing that these variables have bidirectional causal influences on one another over time. Data to test for reciprocal causality are drawn from three waves of the Rochester Youth Development Study. Results suggest that simple unidirectional models are inadequate. Associating with delinquent peers leads to increases in delinquency via the reinforcing environment of the peer network. Engaging in delinquency, in turn, leads to increases in associations with delinquent peers. Finally, delinquent beliefs exert lagged effects on peers and behavior, which tend in turn to “harden” the formation of delinquent beliefs.

This paper uses data from an ongoing panel study of urban youth to examine the causes and correlates of hidden gun carrying among young urban males. The analysis assesses the changing impact of gang membership, drug sales, and peer gun ownership for protection on gun carrying at nine separate points over the early adolescent to young adult life course. I n early adolescence, gang membership is a strong motivation for gun carrying. At somewhat older ages, drug dealing, particularly high drug sales, and illegal peer gun ownership replace gang membership as the primary determinants of illegal gun carrying.Criminologists are searching for an explanation for the increase in homicide and other violent crimes that occurred in the United States between 1985 and the early 1990s. During this period, the rate of murders committed by juveniles doubled while the murder rate among adults actually declined.* The increase has been most dramatic for the nation's minority youth. For example, the homicide rate for