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 and ended in February 2020 concluding in an ELI-UNIDROIT Instrument. This volume consists of the ELI-UNIDROIT Instrument on the European Rules of Civil Procedure, which features Rules and accompanying comments. It takes into account the diverse traditions in Europe concerning civil procedure law and aims to find a common thread in them. Therefore, it not only considers the similarities but also the differences in order to gain a solution that does not favour one legal system but combines aspects of all legal systems.