Data were obtained on the incidence of mental illnesses in Negro troops stationed on an isolated island in the Southwest Pacific and comparisons made with similarly situated white troops.1. The incidence of psychoneuroses and psychoses was found to be appreciably higher among Negro than among white troops.2. The Negro appeared less well equipped by virtue of emotional and intellectual resources to adjust to war zone conditions of bodily hazard and isolation from women.3. The rigors of military discipline, long working hours, and necessarily meager facilities for entertainment in the war zone acted to enhance already existent feelings of maltreatment and racial discrimination among Negroes.4. Screening out by the induction centers of those unfit for military service because of mental and emotional defects seemed to have been less painstakingly performed among Negroes than among white men and this may have been a factor in the high incidence of psychiatric illness.5. In many instances the officers were unsuitable to lead Negro troops.Abstract Teaser