Another policy paper on differentiation in the EU’s foreign, security and defence policies was published within the Horizon 2020 project EU Idea Work Package 5 led by FIIA. The publication “Differentiated Cooperation in European Foreign Policy: The Challenge of Coherence” authored by Giovanni Grevi (EPC), Pol Morillas (CIDOB), Eduard Soler i Lecha (CIDOB) and Marco Zeiss (EPC) analyses why the Treaty-based mechanisms of differentiation in EU foreign policy have been used so rarely, and explores instances of informal differentiation. FIIA also contributed to another EU Idea policy paper “Differentiation in ASEAN, ECOWAS and MERCOSUR: A Comparative Analysis” written by FIIA’s Senior Research Fellow Bart Gaens, and Bernardo Venturi (IAI) and Anna Ayuso (CIDOB).