The bioethical reflection about the so-called “risky behaviors” starts from the observation of human action in order to understand its positive or negative value in the light of well explained anthropological models. The definition of a positive or negative judgment about such behaviors, whose social diffusion in the globalized world is increasing, must necessarily start from the analysis of medical-scientific and sociological data concerning the positive or harmful effects of these behaviors on people’s lives and society. In a final analysis only, this definition of a judgment is meant also to assign responsibilities to the involved moral subjects at their respective levels: individual, community, institution. Following this thread, the course will analyze the various categories of risk behaviors, focusing above all on addictions, with a particular attention to the adolescent world.