We investigate the relative importance of the equity and efficiency motives for altruistic behavior using an artefactual field experiment. A set of binary dictator games is implemented within a telephone survey conducted with a representative sample of adults. The results indicate that, overall, equity plays a more important role than efficiency for the decision to give. Relative to the general population, young individuals are less concerned with inequality, while individuals with higher education are more concerned with social welfare. This indicates that lab experiments, generally implemented with young and educated university students, may lead to overestimate the importance of efficiency, relative to equity, as a determinant of altruistic behavior.