This thesis is about police reports concerning school violence in Sweden involving children below the age of criminal responsibility. Police reports about incidents caused by pupils in Swedish compulsory schools have increased since at least the 1980s. In research on violent, threatening and insulting acts among children in schools, incidence and causes are often studied in terms of bullying and degrading treatment. Criminological studies on children's violent acts, in schools, is mainly based on information on children aged 15 and over. Research on why police reports are filed about younger children in compulsory schools is limited. The aim of this thesis is to describe and analyse school-related police reports, in relation to children’s unwanted actions in compulsory schools with the goal of understanding the intentionality in every day practice. The empirical material consists of four studies of which three have been conducted using qualitative methods through analysing legal documents, using content analysis of texts in school-related police reports and interviews with Principals. The fourth study has been carried out with statistical analysis of school-related police reports. The results of the studies are presented in four papers. This thesis takes the approach from modern sociology which is used both as perspectives and theory. The perspectives concern modernity, social control and cultural sensitivity. The theoretical framework is based on theory of systems and lifeworld. The concluding analysis shows local differences in the assessments on which action will be reported to the police. It is mainly Principals who make reports to the police but also parents. Principals’ police reports are based on social commitment and early intervention and parents report concern about repeated school bullying of their children. Despite diverse local practices certain patterns appear. Boys in the 13-14 years age group are the ones most often seen as perpetrators in the police reports. Two particularly prominent patterns become visible at the school level. Most police reports are related to schools with low grades and to so-called resource schools. This indicates that the unwanted actions of disadvantaged children are more often reported to the police than the actions of other children. The filing of police reports can be understood as a result of difficulties among adults to reach common understanding on how children’s problems should be handled in school systems everyday practice.