People who are cheerful have better social relationships. This might be the case because happy faces communicate an invitation to interact. Thus, happy faces might have a strong motivational effect on others. We tested this hypothesis in a set of four studies. Study 1 (N = 94) showed that approach reactions to happy faces are faster than other reactions to happy or angry faces. Study 2 (N = 99) found the same effect when comparing reactions to happy faces with reactions to disgusted faces. Supporting the notion that this effect is related to motivation, habitual social approach motivation intensified the motivational effect of happy faces (Study 3, N = 82). Finally, Study 4 (N = 40) showed that the reaction-time asymmetry does not hold for categorization tasks without approach and avoidance movements. These studies demonstrate that happy faces have a strong motivational power. They seem to activate approach reactions more strongly than angry or disgusted faces activate avoidance reactions.