Summary The Belgian Dominican friar Antoninus Hendrik Thomas published a critical reconstruction of the earliest Constitutions of the Dominican Order. He identified meticulously where Saint Dominic and his first brothers had borrowed material from other religious and secular juridical systems, as well as where they had been original, thus uncovering the foundational charism of the Order. Even today, researchers in the field regard Fr Thomas's work as indispensable. Unfortunately, many of his insights are difficult to access for a wider audience, since Fr Thomas wrote his work in his native language, Dutch. To mark the eighth centenary of the death of Saint Dominic in 2021, the Belgian Dominican province therefore decided to publish Fr Thomas's work in an English translation, as well as to complement this with a selection of essays written by contemporary experts, who - from their particular perspectives - engage with Fr Thomas's main insights. The essays deal with the historiographical tradition to which Fr Thomas belonged, the Premonstratensian, Cistercian and secular sources of the Constitutions, the manuscript tradition and editing process of the earliest Constitutions, and their reception in the first century of the Order and by the late medieval observant movement. TABLE OF CONTENTS Introduction, Anton-Marie Milh OP & Mark Butaye OP Sigla PART I: Essays Et ut maxima est Historiae necessitas, non minor est utilitas. Belgian Dominican Historians in the 19th and 20th Centuries Anton-Marie Milh O.P. tat actuel des recherches sur les statuts de l'Ordre de Pr montr aux XIIe et XIIIe si cles Herman Janssens O.Praem. Les cisterciens et l'essor de la pratique statutaire, des origines au d but du XIVe si cle Alexis Gr lois Les dominicains, les coll ges et les universit s. Une pauvret savante au XIIIe si cle ? Laurent Waelkens & Wouter Druw A Manuscript and Its Editions. AGOP XIV A4, folios 28r-47r ? Wolfram Hoyer O.P. Les constitutions dominicaines au Moyen ge. Histoire et perspectives ditoriales Florent Cygler La premi re l gislation dominicaine dans les r cits fondateurs de la m moire de l'Ordre Anne Reltgen-Tallon Reformatio or deformatio? The First Observant Friars and the Dominican constitutions in the Light of Henry of Bitterfeld's Treatise on Reform of the Order Anna Zajchowska-Bo?tromiuk PART II: Antoninus Hendrik Thomas OP, The Earliest Constitutions of the Dominicans. Antecedents, Text, Sources, Origins and Development (1215-1237), with an Edition of the Text. Translated into English by Brian Heffernan Introduction Abbreviations and sigla Chapter I. Antecedents. Monastic legislation up to the beginning of the thirteenth century Chapter II. The text Chapter III. The sources Chapter IV. Origins and development General conclusion Appendices Appendix I. Text Edition Appendix II. Comparative list of the chapters in the first distinctio of the Dominican text (C) and in the Constitutiones S. Mariae Magdalenae (M) Appendix III. Comparative list of the chapters in the second distinctio of the Dominican text (C) and in that of the Friars of the Sack (S) Appendix IV. The ordinances of the chapter of 1236 in the texts of the constitutions Appendix V. Relationship of the various constitutions and manuscripts to the Constitutiones Antiquae O.P. Appendix VI. Comparative list of the chapters in the first distinctio of the Dominican text (CA) and in the Consuetudines of Pr montr (Pa and Pb) Appendix VII. The sources of the Dominican constitutions Index of part II