To begin our study of gang membership, we examine the prevalence and duration of gang membership for the total sample of the Rochester Youth Development Study and for its major demographic subgroups, compare gang members and nonmembers in terms of delinquent behavior, and then assess the proportionate contribution of gang members to the overall volume of crime.

The Prevalence of Gang Membership

Ever Prevalence

The prevalence of being a gang member at any point up to Wave 9, which essentially covers the high school years, is 30.9% of the total sample (Table 3.1). Thus, although most (69.1%) in this urban sample were not gang members, gang membership is not rare.

This prevalence rate is rather high when comparisons are made with results in other studies. For example, Klein (1971) estimated that in the four geographical areas covered by his study only about 6% of the gang-age youths in those areas were actually gang members. A similar approach, with similar results, has been used by other field researchers – for example, Moore (1978) and Vigil (1988). In a survey of eighth graders in 11 American cities, Esbensen and Winfree (1998) found that 11.8% of the respondents were gang members. Our estimate, based on a measure of lifetime prevalence rather than a point estimate or annual rate, highlights the importance of looking at gang membership as a trajectory that unfolds with age.