Dissonance theory and incentive theory call for different predictions concerning the relation of reward and attitude change after a person has performed some counter-attitudinal behavior. According to dissonance theory a negative, and according to incentive theory a positive relationship is expected. An experiment was conducted in West Germany testing the interactions of choice versus no choice and public versus anonymus (private) essay-writing. A dissonance effect was predicted for the choice/public condition and an incentive effect for the no choice/anonymus condition. The results support these predictions.