The radical novelty of modern society consists of the global autonomy and dynamics of communication systems such as the economy, polity, science, law, health, the arts, sport, and intimacy. They are at the core of our living environment. With this systematic study of functional differentiation in sociology, Rudolf Stichweh fills an astonishing gap in sociological research. To do so, he combines essays and case studies instructive for both practicing social scientists and the general public interested in a sociological understanding of modernity.