Analysis of the rising capacity for, and pro-active strategy in, coordination within the Secretariats-General of the European Commission and Council has concentrated on their effects within these respective institutions. Little attention has been paid to its potential importance for the dynamics of the interactions between these institutions. This article illustrates that formal, institutionalised structures of coordination developed within an institution have an important bearing also on the relations between institutions (e.g. in inter-institutional negotiations). It also shows that institutions lacking formal coordination capacities may overcome this disadvantage through high-commitment negotiation strategies or informal coordination efforts. The empirical analysis exploits the negotiation process leading up to the creation of the European External Action Service (EEAS) as a case-study.