This volume was developed as part of a cooperative project of the European Law Institute (ELI) and the International Institute for the Unification of Private Law (Unidroit), dealing with civil procedure law. The long-term project began in February 2014, as a joint endeavour to adapt the American Law Institute/Unidroit Principles of Transnational Civil Procedure to the European legal environment, and ended in 2020 with the approval of the ELI-Unidroit Model European Rules of Civil Procedure. Featured in this volume, the Rules are accompanied by comments. They take into account the diverse traditions in Europe concerning civil procedure law and aim to find a common thread in them. Therefore, they not only consider the similarities but also the differences in order to gain a solution that does not favour one legal system but combines aspects of them all, fostering effectiveness and fairness in civil procedure.