Supply reduction efforts by drug law enforcement departments are a significant factor in improving the effectiveness of drug control policies. The performance of drug law enforcement departments is one of the most important concerns for policy makers. Therefore, improving the performance of these departments is crucial in order for governments to constrict illegal drug markets and prevent illegal drug distribution. The literature suggests that social capital may have significant impacts on organizational performance. Using survey data from 12 city law enforcement departments in Turkey, this study examines the effects of three social capital dimensions (structural, relational, and cognitive dimensions) on the perceived performance of drug law enforcement departments by using structural equation modeling. The results of this conceptually grounded and empirical study suggest that drug law enforcement departments should pay close attention to promoting social capital among officers in order to fight effectively against drug trafficking.