Adolescence and young adulthood are significant periods of one’s life regarding the onset of problematic substance use, since the abuse of alcohol, tobacco and other illegal substances regularly starts in these life periods. Regarding the development of substance use disorders, adolescence is considered to be a critical period of life, since substance use and dependence occurring in this life period are very likely to lead to addiction in adulthood, medical treatments, comorbid psychiatric disorders, physical illnesses and death. Among the bio-psycho-social risk factors for substance use
disorders the transition from primary school into secondary school (which coincides with the transition from early adolescence to adolescence) is a very significant one, which makes young adolescents vulnerable for psychological problems. This transition period proceeds around ninth grade. In young adulthood additional risk factors can occur, which increases the likelihood of the first use of psychoactive substances and of the development of substance use disorders. In adolescence and young adulthood the identification of risk factors for substance use disorders are vital for preventive and
interventive purposes. In this lecture the most important predictive and protective factors will be reviewed and outlined and the measures of prevention and intervention will be investigated as well.