This article introduces the idea of informal plurilateralism as a form of policy-making. I show how ideas are mooted and moulded and then filter into technocratic systems of governance at the national level, where these are normalised into the formal, public discourse. I draw on archival material to show how informal plurilateralism has crept into policy-making in international fora on migration, pushing aside more transparent processes, particularly the more openly negotiated multilateral agenda. Informal plurilateralism tends to be portrayed as a welcome addition to formal and informal multilateralism, suggesting that, on the basis of ideational affiliation, policy-makers move to extra-institutional and opaque fora to consult on problems they commonly identify, such as the perceived loss of control over immigration into Europe. Such a benign presentation obscures the closed and non-transparent nature of these negotiations.