The present study examines the influence of pre-existing individual differences in social value orentations, or preferences for certain patterns of outcomes to oneself and others (McClintock, 1978), on perceptions of rationality in a social dilemma. In Experiment 1 conducted in Groningen (the Netherlands), it was found that people with pro-social orientations expected more cooperation from another described as intelligent than from another described as unintelligent, whereas individualists and competitors expected relatively more cooperation from another described as unintelligent. The cross-cultural generalizability of this finding was examined and supported in Experiment 2 which was conducted in Santa Barbara (U.S.A.). Results from both studies are consistent with the Goal Prescribes Rationality Principle (Van Lange, Liebrand and Kuhlman, 1990) which assumes that people with pro-social (cooperative) orientations would perceive rationality in social dilemmas primarily from the collective perspective, whereas individualists and competitors would take a strong egocentric perspective on rationality. In addition, we found a strong relationship between expectations of other's cooperation and own cooperative behaviour when the other was described as intelligent. The strength of this relationship was reduced, particularly for individualists and competitors, when the other person was described as unintelligent.