The issue of whether human populations differ in brain size remains controversial. Cranial capacities were calculated from external head measurements reported for a stratified random sample of 6,325 U.S. Army personnel measured in 1988. After adjusting for the effects of stature and weight, and then, sex, rank, or race, the cranial capacity of men averaged 1,442 and women 1,332 cm3; that of officers averaged 1,393 and enlisted personnel 1,375 cm3; and that of Mongoloids averaged 1,416, Caucasoids 1,380, and Negroids 1,359 cm3.