This report is an attempt to add to the existing information about cannabis use, its correlates, and its effects. The sample population consisted of self-admitted abusers of various drugs, identified shortly after entering the Air Force. The subjects (N=4688) were located through the Drug Control Office at Lackland Air Force Base. Variables studied were race, hometown, Aptitude Index, years of education, age or time of enlistment and performance in the Air Force. Study results indicate that: (1) A positive relationship exists between the extent of cannabis use and abuse of other drugs (hallucinogens, amphetamines, barbiturates, opiates, and volatile substances); (2) The percentage of cannabis users is proportionally greater in the North-Northwest and Far West-Pacific Coast than in the Mid-Atlantic, North Central and Far South - Southwest areas; (3) The greater the cannabis abuse, the more likely the subject is to have lower aptitude and fewer than 12 years of education; (4) Cannabis is the drug of preference among whites although Black users abuse it more frequently; and (5) Cannabis users have lower performance ratings and promotion rates compared to the control sample. (EK)