Psychologists have been an integral part of national security agencies since World War I, when psychological science helped in personnel selection. A robust infrastructure supporting wider applications of psychology to military and intelligence problems developed further during World War II and the years following, primarily in the areas of testing, human factors, perception, and the decision sciences. Although the nature of the attacks on 9/11 raised the level of perceived need for increased human-based intelligence, the impacts of psychologists on the policies and practices of national security agencies in the decade since have not increased significantly.