The present study examined the evolution of the diagnostic criteria from the early writings of Sigmund Freud to the current DSM-IV. Freud's original model of neurosis, known as Seduction Theory, was a post-traumatic paradigm which placed emphasis on external stressor events. In 1897, due to a confluence of factors, he shifted his paradigm to stress intrapsychic fantasy as the focus of analytic treatment for traumatic neurosis. Freud's thinking influenced both the DSM-I and II classification of stress response syndromes as transient reactive processes. However, it is evident from his lectures in 1917-1918 that he understood the interrelatedness of what today is the four diagnostic categories in the DSM-IV.