This chapter describes the system of public enforcement under the Competition Act 1998. Reinforced by the Enterprise Act 2002 and Enterprise Regulatory Reform Act 2013, the Competition Act provides a set of procedural rules of investigation for the enforcement of the Chapter I and II prohibitions. After a section on complaints, it considers the extent to which it may be possible to receive guidance from the Competition and Markets Authority (‘the CMA’) on the application of the Act. It then deals in turn with enforcement of the Competition Act 1998, the criminal cartel offence and company director disqualification. This is followed by an overview of the concurrency provisions, stating that the CMA works hand-in-hand with the sectoral regulators. The final two sections discuss the appeal mechanism under the Competition Act and the possibility of Article 267 references to the Court of Justice.