Psychology responded to the national needs in World War I and World War II and was itself transformed. National need calls a third time: unprecedented levels of posttraumatic stress disorder, depression, suicide, and anxiety along with a need for a resilient Army capable of meeting the persistent warfare of the foreseeable future. As a large part of the Comprehensive Soldier Fitness program, positive psychology is meeting this need with new tests, with new fitness courses, and with resilience training. These developments may transform the practice of psychology and psychology's relation to medicine and education.