This paper examines the structure and domestic political relevance of foreign policy beliefs in contemporary Britain. Confirmatory factor analyses (CFA) of data gathered in five national surveys conducted between May and September 2008 show that the British public’s foreign policy beliefs are organized by two latent factors, which we label Liberal Internationalism and British Militarism. These factors closely resemble those reported in studies of the foreign policy beliefs of the American public. Analyses reveal significant covariation between the two foreign policy belief factors and voting intentions, as well as with partisanship and feelings about party leaders—key predictor variables in voting behaviour models. These relationships remain significant in the presence of several controls, including measures of incumbent government performance in domestic and foreign policy domains. Demonstrating that foreign policy beliefs matter for the fates of political parties and their leaders helps to explain how public opinion in democratic politics affects the conduct of international relations.