The problem of concurrent proceedings is a highly topical one, as public administrative enforcement in many jurisdictions escalates, with record-breaking fines. This book examines and explains the procedural complexities of concurrent proceedings in competition law, focusing on parallel or sequential administrative, criminal, and civil proceedings. The book begins with an analysis of the legal framework, including concurrent enforcement of competition law, administrative and judicial proceedings, as well as an overview of the relevant legal principles. The second part discusses the interplay between administrative, civil, and criminal proceedings, including stays, the effect of administrative decisions, disclosure and admissibility of evidence, and the criminalisation of cartels. The third part deals with international commercial arbitration, covering arbitration of competition law disputes in the European Community and the US, and arbitration and concurrent proceedings. The fourth part evaluates the tactical implications of concurrent proceedings, and leniency and concurrency. The book has now been revised and updated with developments in jurisprudence across the US, UK, and EU.