The longitudinal study focused on 5,360 legally authorized purchasers. The main outcome measures were: (1) the adjusted relative risks for the purchase of an assault-type handgun for persons with and without criminal histories and (2) the adjusted relative risk for new criminal activity during the 3 years after handgun purchase for purchasers of assault-type handguns and other handguns. The relative risks were adjusted for sex and race/ethnicity; 4.6 percent of handgun purchasers with a criminal history and 2.0 percent of those with no criminal history purchased handguns. In addition, among handgun purchasers who had a criminal history, purchasers of assault-type handguns were more likely than purchasers of other handguns to be charged with new offenses, including offenses involving firearms or violence. Among those who had previously been charged with violent offenses, those who purchased assault-type handguns were more than twice as likely as purchasers of other handguns to be charged with a new offense and three times as likely to be charged with a new offense involving firearms or violence. Findings indicated that in this population, the purchase of an assault-type handgun was associated with both prior and subsequent criminal activity. Tables, figure, and 25 references (Author abstract modified)