This volume presents the proceedings of the 15th International Workshop of Groupware (CRIWG 2009). The conference was previously held in USA, (- aha)in 2008, Argentina (Bariloche)in 2007, Spain (Medina del Campo) in 2006, Brazil (Porto de Galinhas) in 2005, Costa Rica (San Carlos) in 2004, France (Autrans) in 2003, Chile (La Serena) in 2002, Germany (Darmstadt) in 2001, Portugal (Madeira Island) in 2000, Mexico (Cancun) in 1999, Brazil (Buzios) in 1998, Spain (El Escorial) in 1997, Chile (Puerto Varas) in 1996, and Portugal (Lisbon) in 1995. The CRIWG workshops seek to advance theoretical, experimental, and - plied technical knowledge of computer supported collaboration. In the CRIWG workshops, researchers and professionals report ?ndings, exchange experiences, and explore concepts for improving the success of people making a joint e?ort toward a group goal. Topics of discussion are wide ranging, encompassing all aspects of design development, deployment, and use of groupware. CRIWG embraces both mature works that are nearly ready for publication in peer review journals, and new, cutting-edge works in progress. A total of 30 papers were accepted for presentation this year-16 full papers and 14 works in progress.Papersweresubjectedtodouble-blindreviewbyatleastthreemembers of the Program Committee. The papers are organized into nine sessions, on eight di?erent themes: Mobile Collaboration, Social Aspects of Collaboration I & II, Technologies for CSCW, Groupware Evaluation, CSCW Design, Geo Collaboration, Collaborative Learning and Modeling CSCW.

This book constitutes the refereed proceedings of the 24th International Conference on Collaboration and Technology, CRIWG 2018, held in Costa de Caparica, Portugal, in September 2018. The 11 revised full papers presented together with 6 short papers were carefully reviewed and selected from 32 submissions. The papers published in the proceedings of this year span dierent areas of collaborative computing research, from collaborative learning to collaboration through social media and virtual communities.