Implications for Theory and Practice

	There are national implications from the two studies. The consistency of results and conclusions obtained in the two studies, which were conducted in two diverse communities, suggests that similar dynamics are likely to be operating in other areas. Given the recent spread of gangs to more and more cities across America (Thornberry, 1998), these findings underscore the importance of developing effective gang prevention and suppression programs.
	Gang membership has an independent contributing role in the etiology of delinquency over and above other risk and protective factors. These findings point to the tremendous importance of street gangs to understanding the dynamics of delinquency, especially serious and violent delinquency. They also indicate that it may not be enough to intervene only with regard to risk factors in the family, school, and similar areas. Specific attention must be given to understanding the dynamics of gangs that produce these effects and then in developing appropriate intervention programs.
	Preventing youth from joining gangs holds promise for preventing and reducing crime and substance use. Because gangs have such a major effect on delinquent behavior, prevention efforts aimed at reducing delinquency and substance use should seek to prevent and reduce gang involvement.
	Determining why youth join and leave gangs may provide information for prevention programs. Because gang members are so much more involved in delinquency and substance use than nonmembers, understanding why they join and leave gangs may have great practical value. Such an understanding may lead to programs to keep some youth out of gangs in the first place or to shorten periods of active membership for those who do join. If successful, these programs should have an impact on reducing the level of juvenile delinquency and drug involvement.

Gang Membership, Delinquent Peers, and Delinquent Behavior	Juvenile Justice Bulletin · October 1998