The report provides extensive analyses of both sociometric and attribute data gathered on Cook County, Ill., inmates and analyses of data on delinquent youth gangs in Los Angeles. Correspondences between sociometric position and prior drug histories were found, indicating a new way for potentially identifying 'trouble-making' blocks. New methods of classification were developed to perform these analyses. These methods include CONCOR (CONvergence of Herated CORrelations), MAPCLUS (MAthematical Programming CLUStering), and INDCLUS (INdividual Differences CLUStering). Traditional multivariate techniques such as multiple discriminant analysis were also used. The techniques developed by the project offer widely available methods of studying the contact structure of inmates and delinquent gang members. Other possible applications, on a different level of social structure, include the flow of resources and contacts between agencies in a local interagency organizational network. Study data and instruments and about 20 references are included. For appended material, see NCJ 88433-39. (Author summary modified)