Background: An increasing number of empirical studies indicate that infants, toddlers and preschoolers may suffer from non-transient mental illnesses featuring developmental psychopathology. A few innovative child psychiatric approaches have been developed to treat infants, toddlers and preschoolers and their families, but have not yet been conceptually presented and discussed in the framework of different healthcare systems. The organizational and clinical experience gained while developing specific approaches may be important across disciplines and guide future developments in psychiatric treatment of infants, toddlers, preschoolers and their families. Results: This article introduces the Preschool Family Day Hospital for Infants, Toddlers and Preschoolers and their Families at Münster University Hospital, Germany. This hospital is unique in the German healthcare system with regard to its social-service institution division of labor. Specifically, it uses an intermittent treatment approach and an integrated interactional family psychiatric approach to treat children and their parents as separate patients. This multidisciplinary, developmentally and family-oriented approach includes components of group treatments with children and separate treatments with parents. Specific techniques include video-assisted treatments of the parent–child interaction, psychiatric and psychotherapeutic treatments for parents, and conjoint family therapies that include both parents and siblings. Conclusions: The Family Day Hospital for infants, toddlers and preschoolers and their families offers innovative family-oriented treatments for those who suffer from a wide range of severe child psychiatric disorders that cannot be sufficiently treated in outpatient settings. Treatment is based on the need for family-oriented approaches to the early psychiatric treatment of infants, toddlers and preschoolers. Family day hospitals are an innovative approach to preschool child psychiatry that requires further evaluation.