This study is aimed at contributing to the ongoing discussion on the comprehensive approach at EU level. The first part offers an overview of the development of this concept from the adoption of the European Security Strategy (ESS) to the entry into force of the Lisbon Treaty. It is followed by an assessment of the architecture and mechanisms created in the post-Lisbon phase, looking in particular at the organization and functioning of the European External Action Service (EEAS), with a view to set the institutional and policy framework for the current implementation of the comprehensive approach, especially in the field of crisis management. The analysis of the effective operationalisation of this concept on the ground is conducted through two main case studies: the EU’s engagement in the Sahel region and the Horn of Africa.