The Philosophy of Sociality examines the nature of sociality in its various forms, with special emphasis on collective intentionality. Raimo Tuomela begins with a distinction between the "we-perspective" and the "I-perspective." His study of strong collective intentionality -- as expressed byjoint intentions, collective commitment, group belief, authority-based group action, and other phenomena -- outlines the circumstances under which an individual is required to think and act as a group member. By developing a systematic theory of sociality, Tuomela investigates such topics as socialinstitutions, cooperation, cultural evolution, and group responsibility. In The Philosophy of Sociality Tuomela asserts that "we-mode" collective intentionality is a conceptual prerequisite for understanding basic social notions. He finds several contexts in which we-mode intentionality is preferable to "pro-group" I-mode intentionality. He ultimately defends anaturalistic view of the social world by arguing that the we-mode is a genetic and cultural adaptation. The Philosophy of Sociality offers new ideas and conceptual tools for philosophers and social scientists in their analysis of the social world.