The neuropsychiatric impact of World War I, World War II, and the Korean War was described in terms such as shell shock, neurasthenia, psychoneurosis, and battle fatigue. For the Vietnam generation, readjustment problems were initially attributed to alcohol or substance use, followed by growing acceptance of persistent stress responses or post-Vietnam syndrome. In 1979, the US Congress directed the Veterans Administration to establish Readjustment Counseling Centers (Vet Centers) to provide community-based counseling options for combat veterans. By 1980, consensus was reached on the first definition for posttraumatic stress disorder (PTSD). However, scientific and political debate raged as to whether PTSD was a legitimate disorder and Vietnam service a legitimate cause; members of Congress called for closure of Vet Centers. The Congressionally funded National Vietnam Veterans Readjustment Study (NVVRS) emerged from this landscape. Completed between 1984 and 1988, the NVVRS provided the first representative study using newly available structured diagnostic interviews based on DSM-III-R. The 17-symptom PTSD definition established by the DSM-III-R would remain largely unchanged for the next 25 years.