Psychologists have been involved in the military since very early in the development of academic and applied psychology. The application of psychology to the development of the Army Alfa and Army Beta group tests of ability for assessing army recruits in World War I was considered as appropriate patriotic contributions to the war effort, even though their wide spread use came too late to have a major influence. World War I also saw the beginnings of pacifist objections to that war with prominent individuals like the philosopher Bertrand Russel being prepared to go to prison rather than support the war. Word War I also saw the beginnings of the wide spread mechanisation of war in terms of machinery and communications. It also saw the beginnings of an awareness of the psychology of trauma or what was termed “shell-shock” as not being due to cowardice although that attitude persisted in some respects into World War II in such individuals as General Patton. World War II saw the further mechanisation of warfare and communications and this has continued to develop at an accelerating rate until the present time. Such has been this technological development, aided in its effective implementation by knowledge and skills developed in Psychology and Ergonomics that it has enabled human operators to be replaced in many dangerous roles by more precisely targeted computerised systems, thus reducing casualties on both sides. Psychology has also made contributions to the organisational aspects of war, and in particular, military leadership, such as Norman Dixon’s book in 1976, On the Psychology of Military Incompetence. There has also been a dark side of Psychology’s involvement in war, in terms of interrogation techniques and strategies to reduce the enemy’s morale. The aim of this panel discussion is to consider what can and should Organisational Psychologists and Ergonomists do to make a positive contribution with respect to war, which has always existed and continues to exist somewhere in the world. In particular, this panel discussion will consider issues concerning what positive contributions have been made, are being made and can be made in the future, what professional and ethical issues are associated with these actual and potential contributions and what professional guidelines should influence and control them.