The SOPHIE study investigates the efficacy of the online-intervention SOPHIE for adolescents with subclinical social anxiety (i.e., indicated prevention) or with a social anxiety disorder in a randomized controlled trial. The intervention group is thereby compared to a care of usual control group. In addition, ecological momentary assessment is used to examine the implementation of the learned contents in the adolescents' everyday life and to frequently assess possible maintaining factors of social anxiety to model them as mediators of change.