The study explored caseworkers understanding of severe behavioral problems in adolescents associated with the public child welfare service. The purpose was to explore their understanding of youth's problems and needs, and to see how this understanding was reflected in their work. The results are based on textual material extracted from semi-structured interviews with nine caseworkers in the public child welfare service. The findings show a homogeneity in caseworkers understanding of severe behavioral problems, where difficulties were understood as complex and largely as a result of poor parenting practices and skills. However, the results show a heterogeneity in their understanding of current precipitating factors, and time of onset of the deviant behavior. The caseworkers emphasized the importance of a holistic treatment approach and differentiated support measures. However, they presented challenges to safeguard the youths' needs within the child welfare service. The results of the study are seen in the context of theoretical approaches and research, and implications for the field are outlined.