This chapter examines the positions of European political parties on nuclear sharing across the five NATO host nations. It begins by outlining the theoretical and conceptual foundations for why political parties are important actors in shaping foreign and security policy. The chapter then compares the stances of far-left, centre-left, centre-right, and far-right parties using party manifesto data from the Comparative Manifesto Project’s Manifesto Corpus. In the second half, it analyses parliamentary activity in four of the five countries (excluding Turkey, where no such activity exists), focusing on voting patterns related to motions critical of nuclear sharing. This analysis draws on novel data covering all parliamentary votes on nuclear weapons in the selected countries.