From April 1996 to September 1997, a two-stage stratified sample of 1,479 CDU's and NCDU's ages 18 and older were recruited through street outreach and a network-based ("snowball") technique. Drug-use status was established by interview and confirmatory urine screen, and injection status was verified by physical examination for scarring or tracks. Face-to-face structured interviews focused on demographic information, drug-use history, lifetime and 12-month health histories, and information on experiences with violence. Violence experienced and observed in the participant's lifetime and in the previous 12 months was assessed. Demographic characteristics of CDU's and NCDU's as observers, perpetrators, or victims of violence and other bivariate relationships were examined separately using chi-square or t tests. The analysis found that CDU's were significantly more likely to perpetrate all violent acts under consideration; and CDU's were significantly more likely than NCDU's to be the victims and observers of all violent acts. These findings are consistent with the literature, which has repeatedly found strong correlations between violence and individual drug users. The authors advise that the sensitive and contextual nature of violence must be considered as the major underpinning of intervention development and implementation. 6 tables and 42 references