The state´s responsibility for the health and well-being of the population was part of the development towards the welfare state. Government agencies at various levels were helpful in surveys and were also the state´s tool for enforcing social policy goals. The main purpose of the essay is to investigate in what way mental health care 1935-1939 was a tool for the growth of the welfare state. The pronounced questions are about what mental health care looked like regarding patients’ activation, mental care in families’ homes, sterilization and forensic psychiatry, and in what way mental health care can be said to have been a state administrative unit. The investigated material is documents from the administration at St. Olof's Hospital in Visby and the source material is examined on the basis of Michel Foucault's theories on discipline, control, exclusion mechanisms and biopolitics. The result of the essay is that mental health care and St. Olof's Hospital can be seen as one of the tools for the growth of the welfare state both as part of the administration, as a prerequisite for biopolitics, and as an entertainer and messenger of norms and discipline.