Vulnerability is a situational rather than a dispositional state. Seen as an internal trait, vulnerability refers to an individual’s inability to withstand the effects of a hostile environment. Childhood vulnerability models in psychology and psychiatry suggest that vulnerability is an inherent, sometimes genetic characteristic of the child. Other models stress the contextual nature of vulnerability. In certain contexts, children are vulnerable due to the hostility and abuse in families or other social systems; being vulnerable is a relational statement about what happens between the child and others. This entry introduces the concept of childhood vulnerability and examines how and why children are vulnerable in many contexts.