This book offers a thorough legal and policy examination of the European Neighbourhood Policy (ENP) as latest grand experiment in achieving coherent external relations for the Union. The book draws on legal and political scholarship to attain a definition of coherence in EU external relations. It argues that traditional definitions such as vertical or horizontal coherence are insufficient and sets out a new definition in order to more accurately capture the reality of EU external relations. The book goes on to look in depth at the ENP, arguing that the innovative nature of the ENP in regard to coherence lies beyond the narrowly defined legal sphere, but stems mostly from its hybrid composition of hard legal, soft legal and non-legal policy instruments.