Sociologically speaking, Islam is what Muslims do. From this premise, the book elaborates a sociology of Islam in three major chapters. They show Islam has operated as a cluster of practical orientations ("lifeworlds") that established it as a presence in three fields of social life: global networks, public philosophies, and participatory ethics. The book argues that all three are poorly understood in recent literature, which tends to focus on one specific problem or another, and then in isolation from global and historical contexts. The book argues that the larger preoccupations of ordinary Muslims--how to imagine a global society; how to guide life in the manner of a total philosophy; and how to relate to the world of daily struggles in forums and social movements--are neither unique to the present period nor to religious life. But the career of a particular religion offers a focused empirical lens through which we may offer meaningful propositions about the more general form of these concerns.