This book constitutes the proceedings of the 44th International Conference on Conceptual Modeling, ER 2025, which took place in Poitiers, France, during October 20–23, 2025. The 22 full papers included in this book were carefully reviewed and selected from 106 submissions. The ER conference is providing a forum for the presentation, discussion, and debate of innovative and emerging ideas, concepts, and methods. They create an environment that encourages experimentation, interdisciplinary exchange, and the exploration of new research frontiers.