This study describes the prevalence and correlates of physical assaults, threats of assault, and workers' perceptions of safety in selected urban employment settings. Questionnaires were mailed to a random sample of 1,763 persons working at various jobs and sites throughout Los Angeles County. Workers were asked to describe their work environments, their perceptions of personal safety at work, and physical assaults and threats they had experienced. Three percent of the respondents reported being assaulted within the previous year and 14% reported being threatened within the previous 30 days. Younger workers, more educated workers, and those who worked with clients or patients were more likely to report assaults. Approximately one third of those who reported threats or assaults described the perpetrator(s) as clients, patients, or persons in legal custody, and one third described the perpetrator(s) as co-workers or supervisors. Fifty-two percent of the workers reported being concerned about their safety at work.