In contrast to a vast literature that provides information and guides about focus groups as a methodological tool, this book is an introduction to understanding focus groups as analytical means exploring socially shared knowledge, e.g. social representations of AIDS, biotechnology or democracy, beliefs and lay explanations of social phenomena. The main emphasis of the book is to examine how to analyse interaction and ideas expressed in focus groups. The book considers, first, different kinds of dynamic interdependencies among participants who hold the diverse and heterogeneous positions. Second, it explores circulations of ideas and contents in focus groups. More generally, the book is concerned with: language in real social interactions and sense-making, which are embedded in history and culture; the ways people draw upon and transform social knowledge when they talk and think together in dialogue; the ways people generate heterogeneous meanings in the group dynamics; and communicative activities and genres represented by different kinds of focus groups. This original approach to understanding focus groups will be of interest to researchers and advanced students in social sciences, communication studies, psychology, and language sciences.