Data were drawn from the National Institute of Justice’s (NIJ) Arrestee Drug Monitoring (ADAM) program, which gathers information about drug abuse among arrestees in urban areas. The Colorado Division of Criminal Justice’s Office of Research and Statistics (ORS) has participated in the program since 1989, gathering data from men and women booked into the Denver City jail. In November 1998 and October 2003, ORS asked arrestees about firearm possession and use; this report presents these findings. Participants were 348 Denver arrestees in 1998 and 253 Denver arrestees in 2003. In 1998, 30 percent of arrestees reported they “ever” possessed a firearm; in October 2003, the percentage who reported ever possessing a firearm was up to 50 percent of arrestees. However, while 25 percent of those who possessed firearms reported using them to commit crimes in 1998, by 2003 only 13 percent of firearm possessing arrestees used them to commit crimes. In 2003, 14 percent of arrestees reported that they possessed, at one time, a handgun, shotgun, and a rifle. Only one arrestee reported having a permit to carry a weapon. Approximately half of arrestees in both 1998 and 2003 reported that they had been threatened with a gun; being threatened with a gun and actually being shot at was more likely to occur among those arrestees who possessed a gun. Fourteen percent of arrestees purchased a firearm through a retail outlet and one-third obtained a firearm from a friend. “Protection” was cited as the primary reason for possessing a firearm for 36 percent of the arrestees in 1998 and for 43 percent in 2003. In 2003, 29 percent of arrestees reported possessing or using a rifle and 25 percent of arrestees reported possessing a shotgun. Demographic information about the 1998 and 2003 samples are presented. Figures, tables