Cognitive evaluation theory predicts that contingent rewards should be viewed as more controlling than noncontingent rewards and should be more detrimental to intrinsic motivation. An experiment to investigate the differential effect of performance-contingent and noncontingent rewards on intrinsic motivation yielded results consistent with predictions of self perception theory. Subjects found the task more enjoyable and were somewhat more likely to volunteer for future nonpaid experiments when a payment norm existed. Contrary to the prediction of cognitive evaluation theory, some evidence suggested that contingently paid subjects found the experimental task more enjoyable than the noncontingently paid subjects. However, this result was not consistent across the different measures of intrinsic motivation. (Author/JAC)