Editio Critica Maior (ECM) is a critical edition of the Greek New Testament being produced by the Institut für neutestamentliche Textforschung (Eng. "Institute for New Testament Textual Research"). It is a work (in progress) in multiple volumes, and is intended to cite a more complete list of variant readings than can be incorporated in a manual edition. The University describes the edition as follows:
The Editio Critica Maior documents the Greek textual history of the first millennium based on Greek manuscripts of special relevance for the textual tradition, on older translations and on quotations of the New Testament in ancient Christian literature. Based on genealogical studies of the material prepared for the first time with this completeness the text is being newly reconstructed. The selection of manuscripts rests on an analysis of the entire primary tradition. Every selected manuscript is entered into a database with all its readings and registered in the critical apparatus. The edition thus offers information to answer continuative questions: How does the text change in the course of history and why? How was a text received in early Christianity?"
Currently, the volumes include the General epistles, and incorporate only twenty-five changes from the text used in the United Bible Societies' fourth edition of the Greek New Testament and the twenty-seventh edition of the Nestle-Aland. The editors of both single volume New Testaments will incorporate these minor updates in future editions.