AbstractFew studies have combined factors related to social disorganisation and factors related to opportunity theory at the microspatial level, with most studies aggregating to the block group or census tract. This study disaggregates block group census data in and around the vicinity of locations believed to encourage outdoor drug markets in Philadelphia, Pennsylvania, USA. A location quotient analysis finds that drug arrests cluster within a block or two of many suspected crime generators/attractors. Results from a zero-inflated Poisson model suggest some land use variables and factors associated with social disorganisation can help predict the location and size of drug markets; however, at the city level only retail alcohol outlets remained significant when combined with the social disorganisation-related variables, as a predictor of drug markets. The article discusses a number of potential reasons for these findings.