Abstract
Harm is a crucial concept in the ZPD framework. The concept of probable harm to the child forms the outer limit of the zone of parental discretion, marking the point where parents' decisions should be overridden. This chapter focuses on defining and explaining the concept of harm, and the closely related concept of interests, specifically in relation to children. In short, harm is done to a child when she experiences a large setback to her interests. In explaining what might count as a large setback to interests, the authors set out various accounts of what children's interests are in general, and suggest a possible list of children's interests that are specific to healthcare. An assessment of harmfulness involves comparing the overall extent to which a child's various interests are promoted or set back by the different possible options. The authors suggest that, in the end, this will always involve some degree of individual judgment. There is no straightforward formula to calculate whether a parental choice is likely to set back a child's interests so much that it counts as harm to the child.