We introduce agency concerns to social capital theory and predict that managers can use individual social capital to reduce personal effort costs, which is not in the best interest of the firm. To test this prediction, we collect data on all 8,019 hiring decisions from general managers in the National Basketball Association between 1981 and 2011. We find that managers have a clear preference for hiring players through social ties. The probability that a manager hires players from an NBA franchise to which he is socially tied is 27.6% higher than for an untied franchise. To isolate the motivation for this behavior, we complement our data with information on the sporting performance of teams. In line with agency theory, we find that the hiring of players through social ties reduces team performance. The effect is large: on average, each social-tie player reduces team winning percentage by 5.4%. Overall, this paper documents first empirical evidence that decision makers’ use of individual social capital can lead to reduced firm-level performance.