This volume contains written accounts of a number of contributions to the 12th GCLC Annual Conference dedicated to 'Dynamic Markets and Dynamic Enforcement: which competition policy for a world in flux?', held in Brussels on 26-27 January 2017. Like the conference, this volume explores the existence of a connection between: (i) technological changes (digitization); (ii) transformations in market dynamics and business strategies; (iii) challenges to and evolutions in the application of competition principles; and (iv) innovations in enforcement strategies, with possible second-order effects of these novel enforcement strategies on the conduct of proceedings and decisional outcomes. Structured in two parts, this volume discusses successively the interactions between the expansion of dynamic markets, on the one hand, and the application of substantive competition principles and the design of enforcement practices, on the other hand. Hence, together with conceptual reflections on the state of EU competition law enforcement in the new digital ecosystem, the contributions included in this volume discuss topics such as the relationship between competition and innovation, the specificities of multi-sided markets, how big data may raise market power, the benefits and limitations of the settlement and commitment procedures, due process issues related to the involvement of third-parties in competition enforcement, as well as the role of judicial review in dynamic enforcement contexts.