The focus of the study was on commercial armed robbery as opposed to personal or street robbery. Information was obtained from police records of all armed robberies and attempted robberies in 1990. The analysis of police records yielded 146 potential interviewees, and the final interview sample contained 88 incarcerated armed robbers. Findings demonstrated only about one-third of robberies involved the use of firearms. Robbers rarely reported gun availability as an important factor in their choice of weapon, implying that simply reducing the availability of firearms may not be the most effective violence prevention strategy. Offenders made reasonably accurate predictions of financial benefits of their crimes. In addition, offender analysis of potential costs involved in committing armed robbery was neither irrational nor grounded in ignorance of likely outcomes. Further, robbers appeared to tailor their modus operandi to maximize potential financial rewards and reduce likely risks. The authors conclude target hardening and other situational crime prevention measures have uses beyond their primary prevention capabilities. For example, they may aid in the subsequent detection of offenders and may effectively prevent commercial armed robbery. 55 references and 9 notes