Around 1900 a first phase of medicalization of children's lives manifested itself in the Netherlands. A network of institutions and provisions guaranteed a basic level of care and control of infants' and children's health and well-being. In the Anglo-Saxon world this was followed by a second phase of medicalization, focusing on children's mental health. Since the 1920s both in the United States and in Britain psychiatric norms, concepts and categories began to appear in the educational discourse. This article discusses the rise of the mental health point of view in Dutch educational discourses, both liberal and denominational, from around 1930. Unlike developments in the Anglo-Saxon countries, this second phase of medicalization did not proceed at the expense of a behaviorist approach to child rearing. Dutch educationists embraced mental hygiene as an alternative to a moral approach to the child. As children's sins turned into symptoms of mental disorders, parents' responsibility changed from authority and control of children's behavior into the much more demanding management of the emotional parent-child relationship.