This study examines the spatial relationship between drug availability and rates of drug use in neighborhood areas. Responses from 16,083 individuals were analyzed at the zip code level (n = 158) and analyses were conducted separately for youth and adults using spatial regression techniques. The dependent variable is the percentage of respondents using drugs in the past year. Neighborhood drug availability (the major independent variable) was measured by the percentage of non-drug users who had been approached to purchase drugs. Data were obtained as part of the Fighting Back community evaluation. For youth (aged 12 to 18), drug sales in adjacent and surrounding areas were positively associated with self-reported drug use in areas where youth were residents. For adults, drug sales within the neighborhood were negatively associated with drug use, while drug sales in immediately adjacent neighborhoods were positively related to self-reports of drug use. Findings suggest that the areas where rates of drug users are greatest are not necessarily the same area where drugs are sold. Designing strategies to reduce the supply of drugs should receive input from city and regional planners and developers, as well as law enforcement and public health professionals.