Since the European Neighbourhood Policy (ENP) was launched in 2004 it has become one of the most popular fields of study among scholars dealing with European Union (EU) external relations and European foreign policy analysis. This is because, over the past 15 years, the ENP has become the EU’s most important and wide-ranging foreign policy instrument. At the same time, being an umbrella framework and thus, as was pointed out elsewhere, ‘a roof over an expanding system of functional regional integration that moves at different speeds and with different dynamics in different policy fields’ (Lavenex 2008: 939), the ENP’s complexity and contested nature explains why it has become a fluid object of study (Manners, 2012). Initially developed as a substitute for enlargement, aimed at providing countries at the EU’s external borders, without an accession perspective, with deeper political and economic relations, the ENP features a unique combination of characteristics that are at the heart of multiple and diverse research agendas. The ENP, both as a practice and as a field of study, addresses a highly heterogeneous group of countries – Armenia, Azerbaijan, Belarus, Georgia, Moldova and Ukraine in the EU’s eastern neighbourhood, and Algeria, Egypt, Israel, Jordan, Lebanon, Libya, Morocco, Palestine, Syria and Tunisia in the southern neighbourhood – that differ considerably in terms of their political, economic, social and historical development, and legacies. What is more, by subsuming a vast array of policy fields and sectors, it represents a framework of cooperation that sits on the fence between the EU’s internal and external dimension and transcends the intergovernmentalism–supranationalism divide. Also, by seeking to transpose EU norms, values, rules and regulations, the ENP became an expression of, and test case for, the EU’s ambition to develop further its actorness and to establish itself as a power.