This book constitutes the refereed proceedings of the 29th International Conference on Cooperative Information Systems, CoopIS 2023, held in Groningen, The Netherlands, during October 30–November 3, 2023. The 21 regular papers and 10 work-in-progress papers included in this book were carefully reviewed and selected from 100 submissions. They were organized in topical sections as follows: Knowledge Engineering; Deployment and Migration in CISs; Security and Privacy in CISs; Process Modeling; Process Analytics; Human Aspects and Social Interaction in CISs; and Work in Progress.