Brazilian and U.S. student samples responded to measures of behavioral intention, perceived norms, and affect regarding prosocial behaviors. Subjects were randomly assigned to either an anonymous or public condition in answering the questionnaire, and subjects were categorized as either allocentric, i.e., tending to subordinate their personal goals to the goals of others, or idiocentric, i.e., tending to subordinate the goals of others to their personal goals. The Brazilian sample indicated they would do what was expected of them and would enjoy doing so, whereas the U.S. sample reported not only less intention to do what was expected of them, but also less enjoyment regarding adherence to norms. As predicted, U.S. subjects in the anonymous condition showed less willingness to perform prosocial behaviors with high personal cost than U.S. subjects in the public condition, whereas the Brazilians did not respond differently in the two conditions. These results imply that the Brazilians have internalized ingroup norms; the U.S. subjects demonstrated compliance because of social desirability pressures. In collectivist cultures, habits and other such mechanisms of social control may predict pro-social behavior, whereas both habits and attitudes may be necessary to predict pro-social behavior in individualist cultures.