Five studies are reported which examine the free vs. earned reward phenomenon in humans. The 420 subjects were distributed over all grade levels from preschool through college. Candies and coins were used as rewards. In preschool through sixth grade groups, black, as well as white subjects and experimenters were used. The California Psychological Inventory was administered to the college students. In all experiments, subjects had the choice of obtaining rewards one at a time, either by pushing a lever or choosing freely from a filled dish. There was a great preference for obtaining rewards by bar pressing. The preference decreases from nearly 100 percent to about 50 percent as subjects increased in age. No significant differences were found for type of rewards, sex, or race of subject and experimenter, except that males bar pressed significantly more than females in the college group. Two scales of the CPI correlated significantly with bar pressing. (Author/SET)