The use of consciousness-altering substances is a fundamental component of human communities. We describe and examine the bodies of social knowledge that shape the handling of such substances in politics, law, economics, and culture. A particular focus lies on the everyday consumption of psychoactive substances and on those practices and forms of knowledge that are decisive for the successful or unsuccessful integration of consumption into daily life. These aspects are examined within the framework of the ongoing project “Cannabis in Everyday Life.” At the same time, we also investigate the changing perception and interpretation of psychoactive substances and drugs.