An armed robbery alarm system was implemented in 48 different stores in two separate geographical areas for 6 months and 12 months, respectively. The alarms were placed in the two separate areas at different times and all alarms were eventually removed. Thus, multiple baseline and reversal strategies were used to evaluate program impact. A device planted in a cash drawer was triggered whenever "bait" money was removed from the drawer sending an alarm signal directly to police cars and headquarters. Onscene apprehensions of armed robbers within target stores were greatly increased even though the armed robbery systems did not deter robbery incidents nor influence the court disposition of the cases. There was also no crime deterrence, crime displacement, or increased apprehensions in either the immediate neighborhoods of target stores or on a city-wide basis. The cost effectiveness of the program was calculated to be poor even though the program is being maintained because of the absence of an alternative robbery apprehension technology.