This paper integrates genetic and biological data on aetiological risk for anorexia nervosa (AN) with cognitive and psychosocial explanatory models. We have reviewed clinical and basic science data from each of these domains and then used a developmental perspective to formulate a multifactorial threshold model. By positioning interpersonal stress as a central component of this model, psychological, social and biological conceptualisations of AN can be used to generate a data driven, neurodevelopmental hypothesis for the aetiology of this complex disorder.