The intent of this measure is to reduce opportunities for nonresidents to victimize residents. To determine spatial and temporal changes in burglary patterns in one jurisdiction after gate installations, data were obtained from the Merseyside County Police Department for the period before gate implementation (January 1, 1998-December 31, 1999) and a period after implementation (January 1, 2000-June 31, 2003). Data were obtained on the exact location and timing of the installation of alley-gates. The gates protected 106 blocks of adjacent housing that contained approximately 362 residential properties. For the period evaluated, 3,178 gates were installed. All of the gates were located in the City of Liverpool in Merseyside County in northwest England. Findings show that within the alley-gated areas, levels of burglary declined by up to 37 percent after gate installation, taking into account changes in burglary rates in surrounding areas without alley-gates. An indication that the measure reduced burglary opportunities at the rear of the residences was suggested by an increase in the proportion of burglaries in which entrance to the property was gained through other entry points; however, this tactical change for burglars was not sufficiently significant to erase the overall reduction in burglaries after alley-gate installations. 5 figures, 4 tables, and 34 references