The MP, which was conducted between 1954 and 1957, was intended to inhibit or reduce the amount of illegal activity by resident juveniles. Project methods reflected a "total community" philosophy, which assumes that delinquent behavior by urban lower class juveniles is largely influenced by certain community structural features. The MP executed "action" programs directed at three societal units: the community, the family, and the gang. The community program developed and strengthened local citizens' groups so they could improve their response to local problems. Work with families involved intensive psychiatrically oriented casework with families having a history of long-term use of public welfare services. Work with gangs, the major effort of MP, was based on the detached worker or area worker approach used by the New York Youth Board and similar projects. This article describes action methods with street gangs. The MP evaluation examined whether there was a significant inhibition of law-violating or morally disapproved behavior due to project efforts. The evaluation obtained data related to change in disapproved forms of customary behavior, illegal behavior, and court appearance rates. The findings showed no measurable change in such behaviors as a result of project efforts. Future reports will examine why the project had so little impact on delinquency. 2 figures and 43 footnotes