When a child welfare caseworker is deciding whether or not to remove a child from his or her biological parent or parents and to place the child in foster family care, the worker is making one of the most important decisions in both the parent's and the child's life. What is the foundation for this type of drastic intervention? This article reviews the scientific and clinical knowledge base developed to warrant professional intervention by the child welfare caseworker in this situation. Intervention does not appear to have a sufficient scientific or clinical basis in the social work literature to suggest that this is a professional judgment that the child welfare caseworker should be called upon to make. At a minimum, court involvement in the decision-making process is required to provide sufficient justification for state involvement in family life until a firmer base for professional judgment can be demonstrated