The Project on the Social and Cultural Aspects of Economic Development at Harvard's Center for International Affairs interviewed 6,000 men from six developing countries to study the impact on the individual of his exposure to and participation in the process of national and economic modernization. To a striking degree, the same syndrome of attitudes, values, and ways of acting-such as openness to new experience, independence from parental authority, and taking an active part in civic affairs-defines the modern man in each of the six countries and in all the occupational groups of cultivator, craftsman, and industrial worker. Education is the most powerful factor in making men modern, but occupational experience in large-scale organizations, and especially in factory work, makes a significant contribution in "schooling" men in modern attitudes and in teaching them to act like modern men. Those who come from very traditional backgrounds and receive little formal schooling can, under the right circumstances, still become modern in adult life. Modern men in developing countries not only have modern attitudes, but they can be shown to behave differently. Despite popular impressions to the contrary, exposure to the influence of migration and modern institutions does not lead to psychic distress.