The purpose of this study was to gain an increased understanding of the social workers investigative work with children and families where the child has a problematic school absence. The study has a qualitative approach, and the empirical material has been collected through semi-structured interviews with six social workers from social services, all of whom investigate children and families with this problem. The results have been produced with the help of qualitative content analysis that later has been analyzed in relation to systems theory and previous research. The main results of the study shows that the background to children's school absence can be difficult to identify and can vary greatly. In most cases, however, the social secretaries feel that there is an NPF diagnosis related to the child. The social workers experience that the children and families often get in contact with them too late, when the school absence already has occurred for a long time, which makes it more difficult for them to act. It is therefore desirable to get these matters in early. Two success factors in the investigation work are when there is a good collaboration between the child and family as well as the school and BUP(children and adolescent psychiatry). Poor collaboration, limited resources and poorly adapted interventions are, on the other hand, some of the biggest difficulties in the social secretary's investigative work.