Adolescent mental health issues, the role of public health nurse, and inter professional teamwork within the school health service are all discussed. We wanted to learn more about adolescents with mental health issues, as well as the risk factors that may contribute to those issues, as well as how public health nurses (PHN) and other health care providers interact with each other when working with students who are struggling with mental health issues. We employed both quantitative and qualitative approaches in our research. Data from Ung data was used, which comprised 8052 adolescents aged 13 to 16 years. Multiple hierarchical regression and descriptive statistics were used to analyze the data. The interviews with the boys were analyzed using qualitative content analysis. Four focus group interviews included a total of 14 participants, including eight teachers, one social worker, one child welfare worker, a psychologist, a PHN, and two highly trained instructors. A content analysis was performed on the interviews. Study IV included 18 PHNs who were interviewed and analyzed using a phenomenographic technique.