The largest and most comprehensive national gang survey to date, the 1997 National Youth Gang Survey, contacted nearly 5,000 law enforcement agencies across the country. To allow for both comparative and trend analysis, the 1997 survey used the same sample as the 1996 survey. Survey results indicate that the percentage of jurisdictions reporting active youth gangs decreased from the previous year, from 53% in 1996 to 51% in 1997. Some 816,000 gang members were active in some 30,500 youth gangs in 1997, a modest decrease from 1996. Despite these declines, serious problems remain. Every city with a population of 250,000 or more reported the presence of youth gangs. In addition, the number of gang members increased in small cities and rural counties as youth gangs continued to spread beyond the largest cities. Youth gang members were estimated to be involved in 3,340 homicides in 1997, almost two-thirds of which took place in large cities. In response to the proliferation of gangs throughout the country, most law enforcement agencies have established specialized response units. Thirteen appendixes contain supplemental information about gang involvement and the survey methodology. (Contains 31 tables, 18 figures, and 29 references.) (SLD)