This volume constitutes the proceedings of the 28th International Conference on Collaboration Technologies and Social Computing, CollabTech 2022, held in Santiago, Chile during November 8-11, 2022. The 18 full and 4 work-in-process papers presented in this volume were selected from 37 submissions and underwent careful double-blind peer review. The papers focus on innovative technical, human and organizational approaches to expand collaboration support including computer science, management science, design science, cognitive and social science.

This book constitutes the proceedings of the 15th International Conference on Intelligent Tutoring Systems, ITS 2019, held in Kingston, Jamaica, in June 2019. The 14 full papers and 13 short papers presented in this volume were carefully reviewed and selected from 42 submissions. In the back matter of the volume 4 poster papers are included. They deal with the use of advanced computer technologies and interdisciplinary research for enabling, supporting, and enhancing human learning.