Differentiated Europe needs strong institutions. CHALLENGE EUROPE Issue 22 - Challenges and new beginnings: Priorities for the EU's new leadership, September 2014.

Differentiated Europe can be analysed in terms of the three meta-challenges outlined in this publication – stagnation, fragmentation and legitimacy. My argument is simple: stagnation or the prospect of it has been a catalyst for differentiation, fragmentation poses a risk of differentiation gone too far and legitimacy of differentiation is embedded on institutional cohesion and good results.