This study uses data on campaign contributions and methods of network analysis to investigate the significance of interlocking directorates for political cohesion among corporate elites. Using quadratic assignment procedure (QAP) regression, the author shows that social ties formed through common membership on corporate boards contribute more to similarity of political behavior than commonalities of economic interests, such as those associated with operating in the same industry or the same geographic region. Moreover, the politically cohesive effects of directorship ties remain robust even as one moves several links down the chain of indirect ties that connect top corporate officers to one another. The study thus provides empirical support for the thesis that social networks among corporate elites facilitate political cohesion within the business community.Interlocking directorates among major U.S. corporations have been a focus of political and scholarly interest since the early 20th century. In recent decades, advances in computer technology and methods of network analysis have led to a virtual explosion of empirical studies of interlocking corporate directorates. Despite this extensive body of research, important questions remain as to the meaning and significance of director interlocks. As Mizruchi (1996) notes in his review of the literature, the question What do interlocks do? is perhaps the most crucial question confronting interlocks research. Critics of the early studies of director interlocks argued that this research was mostly descriptive and that the social, political, and economic effects of interlocking directorates were more often assumed than empirically demonstrated. Partly in response to this criticism, con-1 I wish to thank