This book constitutes the refereed proceedings of two long-running events held alongside the CAiSE conference and related to the areas of enterprise-, business-process- and information systems modeling: the 27th International Conference on Business Process Modeling, Development and Support, BPMDS 2026 and the 31st International Conference on Exploring Modeling Methods for Systems Analysis and Development, EMMSAD 2026 The conferences were held in Verona, Italy, during June 8&9, 2026. For BPMDS, 11 full papers and 3 short papers were carefully reviewed and selected for publication from a total of 32 submissions. The BPMDS papers deal with a broad range of theoretical and applications-based research topics in business process modeling, development, and support. For EMMSAD, 11 full papers and 4 short papers were accepted from a total of 37 submissions after thorough reviews. EMMSAD focuses on modeling methods for systems analysis and development.