This article tries to reconsider the My Lai Massacre from the standpoint of two official commissions – one led by General William Peers and the other by F. Edward Hebert – investigating the massacre which occurred in My Lai on March 16, 1968. Both commissions tried to propose an objective account of events, as well as explain the behavior of the soldiers and officers and, eventually, analyse the rise of violence among American soldiers in Vietnam. In the end, the Peers Commission blamed officers of the Americal Division while the Hebert Commission asserted that this event was exceptional and caused by individuals. Despite their different approaches, the two commissions produced a great deal of evidence with which historians can write the history of the Vietnam war. These historians can either draw upon the conclusions of the two commissions or criticize their failure to bring about an actual account of the American tragedy in Vietnam.