Public law protection of children challenges one of the fundamental principles of England and Wales that children are best brought up by their parents. Unlimited state intervention in the family is not permitted and the courts have to strike a balance between maintaining stability for children within their family, and protecting them from harm. This chapter considers the statutory duties of the local authority towards children as well as emergency action to protect a child. It examines what has to be proven to obtain a care order and the evidential difficulties connected with this; in particular, the difficulties posed for the courts where harm is caused to a child by an unknown perpetrator. The chapter ends by exploring the options available to the court at the welfare assessment once the threshold criteria have been met.