previous studies of gangs and gang members have not, by and large, placed the study of gang members in a life-course perspective. As a consequence there are a variety of important topics in the study of gangs about which we have inadequate information. They include, first, studies of risk factors in which antecedent variables are linked to the odds of later gang membership and studies of causal processes that attempt to identify why certain youngsters join gangs while others do not. Second, although we know from many studies that gang members are more delinquent than nonmembers, few studies of within-individual change examine the extent to which gang membership itself may facilitate this outcome. Finally, although we have some indication of the short-term impact of gang membership on the individual, we have little information on long-term developmental consequences of being a member of a street gang during adolescence.

In this book, we have tried to flesh out the picture of gang life by focusing on developmental questions within the context of the Rochester Youth Development Study. This study has a number of design features that aid in the examination of these issues. The Rochester study has a representative, community-based sample of an initial panel of 1,000 adolescents followed from early adolescence to early adulthood. Subjects were not selected on the basis of whether they were gang members, and gang membership was observed as it naturally occurred over the life course, if it occurred at all.