Findings were derived from responses to self-administered questionnaires completed by 835 male inmates in six juvenile correctional facilities and 758 male students in ten inner-city public high schools. Both groups of respondents came from families where ownership and carrying of firearms were common and were widespread among respondents' peers. Inmates had lived and students were living in social environments marked by violence and victimization and firearms circulated widely and freely throughout their neighborhoods. Gun ownership and carrying among both inmates and students appeared motivated primarily by a sensed need for self-protection. Guns were a response to the perceived violence and predation of the community, not a matter of status among peers. Gun dealers, respondents who said they had bought, sold, or traded a number of guns. were more involved in crime, more likely to carry a gun and to own all types of weapons, more involved in shooting incidents, and more accepting of shooting someone to get something they wanted. Very few respondents in either sample could be described as hard-core regular drug users. However, use of alcohol and illicit drugs was relatively common and firearms were a common element in the drug business. Members of gangs were more likely to be involved with firearms and with drugs than were members of quasi-gangs, who were in turn more active than juveniles as a whole. Informal commerce in small arms is difficult to regulate and successfully subverts legal measures designed to prevent guns from falling into the wrong hands. Footnotes, references, tables, appendixes