The authors contribute to the existing literature on the determinants of legislative voting by offering a social network-based theory about the ways that legislators’ social relationships affect floor voting behaviour. It is argued that legislators establish contacts with both political friends and enemies, and that they use the information they receive from these contacts to increase their confidence in their own policy positions. Social contacts between political allies have greater value the more the two allies agree on policy issues, while social contacts between political adversaries have greater value the more the two adversaries disagree on policy issues. To test these propositions, we use social network analysis tools and demonstrate how to account for network dependence using a multilevel modelling approach.