Supply reduction efforts by drug law enforcement departments are a significant factor in improving the effectiveness of drug control policies. As with other public organizations, 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 implications for policy makers and practitioners in terms of enhancing organizational performance.Social capital has recently been examined at the organizational level. It may contribute to organizational effectiveness by increasing motivation, solving coordination problems, facilitating information flow between individuals and organizations, and developing knowledge within organizations. Because of the nature of the work, drug law enforcement departments or agencies require information sharing, cooperation, and motivation, all possible derivatives of social capital.Using a measurement model of organizational social capital, this study examines relationships among three dimensions of organizational social capital. The influence of social capital on the perceived performance of drug law enforcement departments is investigated using structural equation modeling. Possible correlations among these dimensions or domains of organizational social capital are also empirically tested.Using survey data from 12 city law enforcement departments in Turkey, this study examines three social capital dimensions: (1) the structural dimension, concerning the extent to which officers within a department informally interact with each other; (2) the relational dimension, referring to the normative qualities of relationships among officers, such as trust and reciprocity; and (3) the cognitive dimension, reflected by shared language, shared interpretation, and shared vision.Four research hypotheses were tested and supported by the statistical results. The study's findings indicate that the relational and cognitive social capital variables have a direct and positive relationship with the perceived performance of drug law enforcement departments. Relational and cognitive social capital, as latent constructs, were shown to have a strong relationship with organizational performance. Structural social capital, however, does not have a direct relationship with but may indirectly influence performance. This result indicates that structural social capital may influence organizational performance only indirectly, through its joint influence with two other social capital domains. On the other hand, strong and positive intercorrelations were found among the three dimensions. The results suggest that social capital is essential for drug law enforcement departments because police officers who know, understand, and trust each other are more likely to work together efficiently and effectively towards achieving organizational performance.According to the findings, informal structures shaped by informal relations among officers within the departments may also be an important factor for organizational performance. Investing in the development of social interactions and networks and building trust within organizations is important in order for administrators to improve organizational performance. The results of this conceptually grounded and empirical study suggest that drug law enforcement departments or agencies should pay close attention to promoting social capital among officers in order to fight effectively against drug trafficking.