Here are collected most of the papers delivered at the Twelfth International Congress of Medieval Canon Law. They are organised into nine sections: Jane Merdinger, Roldán Jimeno, Roger Sabanés Fernández and Bart Wauters contribute to the section on ‘Law, councils and canonical thought in Spain and north Africa’; Wilfried Hartmann, Martin Brett, Christian Lohmer, Nicolás Álvarez de las Asturias, Szabolcs Anzelm Szuromi, José Migule, Viejo-Ximénez and Pier V. Aimone on ‘Texts from Regino of Prüm to Gratian's disciples’; Mary E. Sommar, Anne Lefebvre-Teillard, Thomas Wetzstein, Bronislaw Wenanty Zubert and Silvia di Paolo on ‘The life and legacy of canons and collections’; Henry Ansgar Kelly, Lotte Kéry, Giovanni Minnucci and Helmut G. Walther on ‘Canon law and the other laws’; Anne Duggan, Werner Maleczek, Tilmann Schmidt and Peter Herde on ‘Papal texts’; Detlev Jasper, Georg Gresser, Harald Müller and Jürgen Petersohn on ‘Canon law and popes in action’; Roger E. Reynolds, Richard Kay, Dominique Bauer, Jessalynn Bird, James A. Brundage, Jürgen Meithke and Enrico Spagnesi on ‘Canon law and the liturgy, thought, and practices of medieval Christendom’; Heike Johanna Mierau, Nelson H. Minnich and Herbert Schneider on ‘Canons and councils on the eve of the Reformation’; Alberto Melloni and Paolo Bernardini (together), Charles Reid, Anna Wolodarski and Rudolf Schieffer on ‘Medieval canon law and modern thought, technology and institutions’. Of the forty-one papers, twenty-two are written in English, nine in German, six in Italian, three in Spanish and one in French. The three editors provide a short introduction (pp. xiii–xvi). The full list of speakers and titles of the papers, as delivered at the congress in 2004, are listed in ‘Program and participants’ (pp. xvii–xxvii). Three indices complete the work: ‘people’, ‘works’ and ‘manuscripts’ (pp. 1105–35). As the editors note (p. xiv), a few of the contributions at the congress have been published outside the present volume. In particular, four papers on Gratian's Decretum were included appropriately in vols xxvi and xxvii of the Bulletin of Medieval Canon Law, volumes that were dedicated to the groundbreaking work of Anders Winroth on the composition of the Decretum. The study of medieval canon law remains vigorous – as shown by the present collection of eminent contributions – thanks in good measure to the four-yearly international congress (the most recent was held in Esztergom in 2008, the next is due in Toronto in 2012) and to its sponsor the ‘Iuris Canonici Medii Aevi Consociatio’ (ICMAC). Since an understanding of canon law remains crucial for many academic disciplines, the present work may expect a wide welcome. Congratulations are due to the publisher, Biblioteca Apostolica Vaticana, for the excellent production.