This comparative and theoretical account of the heritage and prospects of socialism in Western Europe characterises socialist political theory as transformative. Socialists counterpose objective social appraisal, such as the theory of capitalism, to implausibly ambitious agents of change - the proletariat or the interventionist state. This framework of analysis generates a comparative account of European socialist parties and their attitudes to international institutions - especially the European Union - and suggests a favourable prognosis for the future of socialism.