A critical issue faced by researchers working in the area of child maltreatment concerns the definition of child maltreatment. Definitional issues fall into two main areas: (1) those primarily of a conceptual nature; and (2) those primarily related to implementation or measurement. This paper presents a set of conceptual definitions of abusive and neglectful behaviours. Note that the proposed definitions are of abusive and neglectful behaviours, rather than child abuse or child neglect per se. The aim of these definitions is to describe the types of actions widely considered to constitute the different maltreatment sub-types. These definitions are followed by legislative definitions of “a child in need of protection” in order to examine the point at which, and the circumstances in which, the state is mandated to intervene to protect children.