This book brings together contributions from researchers within anthropology, psychology, communications, sociology, and cognitive science who are interested in redefining the methods and topics that constitute the study of work. They investigate work activity in ways that do not reduce it to a "psychology" of individual cognition or to a "sociology" of societal structures and communication (whether "micro" or "macro"). A key theme of the book is the relationship between theory and practice. This is not treated as an abstract problem of interest merely to social scientists. Instead, it is discussed as an issue that working people address when they attempt to understand a task and communicate its demands. Mindful practices and communicative interaction are examined as situated issues at work in the reproduction of communities of practice in a variety of work settings including courts of law, computer software design, scientific laboratories, repair and maintenance of advanced manufacturing systems, the piloting of airliners, air traffic control, baggage handling, and traffic management in underground railway systems.