This article presents a new development in European immigration policy. Focusing on France, Germany and the Netherlands, I describe a process of culturalisation of admission and citizenship rules in Europe intended to reinforce liberal values and national identity. I then suggest a two-stage set of immigration-regulation principles: in the first stage, immigrants would have to accept some structural liberal-democratic principles as a prerequisite for admission. While Europe has criteria for state admission, anchored by the Copenhagen Criteria, Europe has not yet formalised definite criteria for immigrants' admission. In the second stage, as part of the naturalisation process, immigrants would be expected to recognise and respect constitutional principles essential for obtaining citizenship of a specific state. I call this concept National Constitutionalism.