This book constitutes the proceedings of the 26th International Conference on Collaboration Technologies and Social Computing, CollabTech 2020. The conference was scheduled to take place in Tartu, Estonia, in September 2020. It was held virtually due to the COVID-19 pandemic. The 10 full and 5 work-in-progress papers presented in this volume were carefully reviewed and selected from 25 submissions.

This book constitutes the refereed proceedings of the 25th International Conference, CRIWG+CollabTech 2019, held in Kyoto, Japan in September 2019. The 12 full papers presented in this book together with 8 work-in-progress papers were carefully reviewed and selected from 28 submissions, and the program also included an invited talk. This year presented a merger of the CRIWG and CollabTech conferences after having been jointly held since 2014. The papers published in this proceedings focus on innovative collaboration technologies and social computing.