“It is commonplace that social interaction is complex. This volume is the first to systematically explore sources and orders of this complexity in various interactional settings. It shows how technical mediation, multiactivity, the presence of several parties, the wealth of multimodal resources, and multi-sensorial perceptions create complicated and fragile constellations and processes in social encounters. In addition to fine-grained in-depth analyses of video recordings, the authors establish complexity as a theoretical lens that allows us to gain unprecedented insights into the fabrics of intersubjectivity and interactional organization in our current societies.” —Arnulf Deppermann, Professor, Leibniz Institute for the German Language, University of Mannheim Everyday social life is deeply tied to the ways in which people talk, interact, and engage in joint activities with each other. This book examines language use and social interaction through the lens of complexity, focusing on how participants establish and maintain shared understanding in multi-layered situations and settings. This book will find readership among students and scholars who use video-based methods and are interested in interaction, intersubjectivity and multimodality. Pentti Haddington is Professor of English language and interaction at the University of Oulu, Finland. Tiina Eilittä is a doctoral researcher at the University of Oulu, Finland. Antti Kamunen is a postdoctoral researcher at the University of Oulu, Finland. Laura Kohonen-Aho is a postdoctoral researcher at the University of Oulu, Finland. Iira Rautiainen is a postdoctoral researcher at the University of Oulu, Finland. Anna Vatanen is a researcher at the University of Helsinki, Finland, and also affiliated with the University of Oulu, Finland. The editors form a team that has worked together on complexity of interaction for several years in the projects iTask: Linguistic and embodied features of interactional multitasking and PeaceTalk: Talk and interaction in multinational crisis management training funded by the Academy of Finland and Eudaimonia Institute at the University of Oulu, Finland.