Business has played a central role in the debate over Britain's place in the European Union. This paper examines the socio-economic characteristics of directors of Britain's largest corporations who affiliated either to Business for Sterling or Britain in Europe. It reports associations between directors' social backgrounds and their probabilities of affiliation. Elite university education, club membership, wealth and multiple directorships were all associated with higher propensities to affiliate. The associations are consistent with the idea that directors' social resources allow them to overcome collective action problems as well as supplying them with the motivations to affiliate. They also indicated that directors form a privileged group in that they have a number of very powerful actors who can take unilateral political actions.