This dissertation clarifies the role and relevance of the body in social interaction and cognition from an embodied cognitive science perspective. Theories of embodied cognition have during the past two decades offered a radical shift in explanations of the human mind, from traditional computationalism which considers cognition in terms of internal symbolic representations and computational processes, to emphasizing the way cognition is shaped by the body and its sensorimotor interaction with the surrounding social and material world. This thesis develops a framework for the embodied nature of social interaction and cognition, which is based on an interdisciplinary approach that ranges historically in time and across different disciplines. The theoretical framework presents a thorough and integrated understanding that supports and explains the embodied nature of social interaction and cognition. It is argued that embodiment is the part and parcel of social interaction and cognition in the most general and specific ways, in which dynamically embodied actions themselves have meaning and agency. The framework is illustrated by empirical work that provides some detailed observational fieldwork on embodied actions captured in three different episodes of spontaneous social interaction in situ. Besides illustrating the theoretical issues discussed in the thesis, the empirical work also reveals some novel characteristics of embodied action in social interaction and cognition. Furthermore, the ontogeny of social interaction and cognition is considered, in which social scaffolding and embodied experience play crucial roles during child development. In addition, the issue what it would take for an artificial system to be (socially) embodied is discussed from the perspectives of cognitive modeling and technology. Finally, the theoretical contributions and implications of the study of embodied actions in social interaction and cognition for cognitive science and related disciplines are summed up. The practical relevance for applications to artificial intelligence and human-computer interaction is also outlined as well as some aspects for future work.