Abstract
We provide an introduction into a highly important research area for the improvement of preventive and therapeutic measures in the field of substance use disorders: a better understanding of core mediators and moderators of change processes, especially during critical phases like onset, progression, cessation and relapse. Based on a brief description of 12 papers on related projects we detail relevant research issues like the role of impaired cognitive control functions or the narrow "window of opportunity" for early interventions during adolescence.