Substance-related disorders are among the disorders with a high psychosocial disease burden worldwide. They typically develop in childhood and adolescence. For young people, who begin to experiment with the use of psychoactive substances in our cultural context, it is particularly challenging to learn the boundaries between normal use and abuse. This book provides a scientifically grounded and practice-oriented overview of the clinical presentation, etiology and pathogenesis, diagnostics, course and prognosis of addiction disorders, as well as development-oriented approaches to addiction therapy and prevention in childhood and adolescence.