Understanding how decisions are made in the complex system of the European Union and identifying the most relevant factors accounting for the dynamics and standstills of the European integration process have been central to scholarly debate on the EU since the 1950s. Many different theoretical approaches have been suggested but, in this study, Arne Niemann develops a new approach to the classic neofunctionalist theory of European integration and assesses his framework on case studies in three important policy areas: EU aid, trade policy, and asylum and immigration.