This book constitutes selected papers of the Second International Conference on Computer-Human Interaction Research and Applications, CHIRA 2018, held in Seville, Spain, in September 2018, and Third International Conference on Computer-Human Interaction Research and Applications, CHIRA 2019, held in Vienna, Austria, in September 2019. The 7 full papers presented in this book were carefully reviewed and selected from 28 submissions for CHIRA 2018 and 36 submissions for CHIRA 2019. The papers selected to be included in this book contribute to the understanding of relevant trends of current research on computer-human interaction, including Interaction design, human factors, entertainment, cognition, perception, user-friendly software and systems, pervasive technologies and interactive devices.