Purpose - The purpose of this paper is to examine ideas and notions in the founding and development of the area of mental health services in school in Sweden, with special focus on school psychology and school social work. Design/methodology/approach - From a history of thought perspective, this paper investigates public Swedish school-related documents from the early 1900s up until the 1980s in order to reveal the influential ideas about school health care, children's needs, and professionals' responsibilities. These ideas are linked to the twentieth century development of the behavioural sciences, the school system, and the welfare state in Sweden. Findings - Two main turning points are identified. The first occurred in the 1940s when psychologists and social workers were invited to become part of schools as experts on children's mental health care, implying that mental health issues had become included in the school's responsibility. The second turning point came in the 1970s when the tasks and the ideational context for the mental health experts changed dramatically. The first turning point challenged the dominant explanation model, a model that relied on scientific references to medicine, and eventually led to an acceptance of psychology instead as dominant provider of explanatory models. The second turning point affected the tension between child and system, and implied a subordination of the needs of the system for the benefit of the needs of the child. Originality/value - This paper highlights how views on children's needs and on the responsibilities of school and its professionals have been constructed and conceptualised differently over time and how those views are connected to changes in science, school, and society.