The private enforcement of competition law through damages actions and/or injunctions before ordinary courts of justice is currently the preferred system in the United States. It is playing an increasingly important role in Europe by supplementing a still predominantly public system based on disciplinary rules enforced by public authorities that do not entail compensation for victims. Compensation can only be achieved through private enforcement, which is already viewed as an alternative to the public system. This work, whose origins lie in the International Conference on the private enforcement of Competition Law held at the University of Valladolid's School of Law offers a comprehensive, pluralist overview of the subject by providing transversal approaches, joint assessment and information on various national experiences alongside more specific contributions that study specific matters of substantive and procedural law, by covering practically all the relevant issues in this field. The work also addresses the main problems of the system vis-à-vis private international law and its connection and interaction with public enforcement. Also available in Spanish language, with the title: La aplicación privada del Derecho de la competencia.