A failure of affect regulation is put forward as central to the development of psychopathology. Giving affect regulation this pivotal role allows one to explain how the various theories of intervention (for example, dynamic, behavioural, medical) can all have relatively similar results. As well, it provides an explanation for the common findings of brain and language dysfunction in psychopathology, the co-occurrence of anxiety disorders in various other mental disorders and the responsiveness of individuals with severe pathology to the affect in their environments. A model is presented linking the reticular, limbic and frontal systems of the brain with the conceptual frameworks used by mental health workers in their efforts to intervene. To illustrate how the model may be used, it is applied to various disorders.