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.