It is customary to argue that foreign policy is very much dominated by the executive, with parliaments wielding limited influence. However, with the exception of the US Congress, legislative–executive relations in the realm of foreign and security policy have attracted remarkably little scholarly attention. Drawing on a principal–agent framework, this collection scrutinises the conventional wisdom of ‘executive autonomy’ in foreign affairs, indicating that even though parliaments have arguably become more involved in foreign and security policy over time, any notions of parliamentarisation need to be treated with caution. While expectations of consensus in the name of the national interest continue to play an important role in foreign policy decision-making, the papers highlight the role of party-political contestation structuring parliamentary debates and votes in this increasingly politicised issue area. This introductory paper introduces the analytical framework and hypotheses guiding the contributions in this collection, summarises their main findings and suggests avenues for future research.