Conceptual Modeling

This book constitutes the proceedings of the 45th International Conference on Conceptual Modeling, ER 2026, held in St. John's, NL, Canada, during October 5-8, 2026.The 20 full papers and 13 short papers included in this book were carefully reviewed and selected from 104 submissions. They are organized into the following topical sections: Conceptual Modeling for Data-Intensive and Regulated Domains; LLMs and AI for Conceptual Modeling; Responsible AI, Regulation and Security; Foundational and Reference Ontologies; Business Process Discovery and Optimization; Modeling Concepts and Modeling Practice; Advances in Ontology Engineering; Requirements Engineering and Modeling Foundations; LLMs and Multi-Agent Systems; Process Modeling and Compliance.