In comparative studies of homicide, many theories compete. This study examined two established theories, stress theory and culture of violence theory, in terms of their ability to explain state-to-state differences in the rate of highly specific types of homicides. The separate and joint effects on homicide committed by handguns, shoulder guns, sharp and blunt instruments, and the mediating role of availability of weapons in the relationship were studied. The investigation was based on homicide data for the United States for 1980-1984, with states serving as the units of analysis. Results showed that legitimate violence was associated with gun ownership, which in turn was associated with homicidal violence. The findings suggest that the institutionalization of violence at the collective level for socially legitimate purposes provides a model which encourages individuals to purchase a gun for self-protection, and the presence of guns increases the risk of an assault becoming lethal. (ABL)