After years of declining juvenile delinquency registered by the police in Switzerland, it seems that there has recently been an increase again. Evidence of this can also be found in surveys on self-reported delinquency. However, such dark field studies are contradictory with regard to the development of juvenile delinquency due to different survey methods. Against this background, a national dark field survey on self-reported delinquency and victim experiences will be conducted among about 4000 14- to 17-year-old adolescents in the respective school types, supplemented by additional samples in two larger cities. This will continue the previous surveys within the framework of the ISRD studies, which were already conducted in 1992, 2006 and most recently in 2013. In addition, comparable surveys will be conducted among 7200 young people in four countries of the former Yugoslavia: Bosnia-Herzegovina, Kosovo, Northern Macedonia and Serbia. This will allow the analysis of different cultural comparative questions regarding juvenile delinquency as well as the current phenomena of cyberbullying / -crime and political extremism, which have hardly been researched in the four Balkan countries so far. Finally, in a longitudinal study, causal influences of considered influencing factors are to be identified by following-up a sample of 8th graders in the 9th grade throughout Switzerland.