As a successor to the Union Internationale de Droit Pénal (UIDP, 1889-1914), the International Association of Penal Law (AIDP/IAPL) was established in 1924, in Paris, France. Symbolically, the Association celebrated its centenary during its XXIst International Congress, held in Paris on 25-28 June 2024, dedicated to artificial intelligence and criminal law.This book comprises the main proceedings of the centenary celebration event of 27 June 2024. It provides insights into the history of the creation of the Association and its role in serving and promoting international criminal justice, human rights and humanity across countries. It also summarizes and assesses its scientific outputs and impact in the respective spheres of general criminal law, special criminal law, criminal procedure, and international criminal law.Gert Vermeulen is General Director Publications of the AIDP/IAPL, Editor-in-chief of the RIDP, and Senior Full Professor of European and international criminal law, sexual criminal law, and data protection law at Ghent University, Belgium.José Luis de la Cuesta is Honorary President of the AIDP/IAPL and Professor of Criminal Law at the University of the Basque Country, San Sebastian, Spain.John A.E. Vervaele is Honorary President of the AIDP/AIPL, Emeritus Professor at Utrecht University, The Netherlands, and Professor in European Criminal Law at the College of Europe, Bruges, Belgium.