This book constitutes the refereed proceedings of two long-running events held along with the CAiSE conference and related to the areas of enterprise, business-process and information systems modeling: - the 26th International Conference on Business Process Modeling, Development and Support, BPMDS 2025 and - the 30th International Conference on Exploring Modeling Methods for Systems Analysis and Development, EMMSAD 2025. The conferences were taking place in Vienna, Austria, during June 16–17, 2025. For BPMDS 12 full papers were carefully reviewed and selected for publication from a total of 39 submissions. The BPMDS papers deal with a broad range of theoretical and applications-based research in business process modeling, development and support. For EMMSAD 13 full papers and 3 short papers were accepted from a total of 37 submissions after thorough reviews. EMMSAD focusses on modeling methods for systems analysis and development.