ABSTRACT In many countries, local supervision is the main activity to control foster care. In Sweden, the legislation stipulates that foster parents have a supervising social worker (SSW) and the foster child an assigned social worker (CSW). This article describes and analyses how child welfare authorities organize and social workers handle the supervision of foster care. The study is based on data (policy documents and 18 individual/group interviews with 43 managers/social workers) collected from six Swedish child welfare authorities. Analytically, the study assumes that the position of foster care between the private and the public spheres paves the way for different ideas regarding how to conduct supervision that can be broadly based on trust or control vis-à-vis foster homes. The findings show that supervision is differentiated and varies more between foster parents and children than between authorities. Supervision approaches are identified that can be analysed as being more or less trust-based (discreet and affirming) or control-based (compensating and interfering) towards foster parents and children, but overall trust-based approaches dominate. The approaches imply different levels of involvement in care and vary regarding emphasis on the private and the public aspects of fostering. The discussion focuses in particular on the potential impact of different supervision approaches on the foster care service.