In the development process, an agent of change must possess psychological qualifications. It was found that the prevalence of mass media enabled the regressive to become the modern. Therefore, development officers must utilize suitable media for receivers to change certain aspects of their behavior. The major policy of the division was to assist hilltribes to reduce or eliminate opium cultivation. The investigation was conducted with Yao, Hmong, and Thin ethnic groups in four villages (Ban Labaoya, Ban Kok, Ban Sakart Nue, and Ban Sakart Klang) in Nan Province on November 3-9, 1983. Socially, the villagers still adhered to their ethnic traditions and practices, but began to accept other religions like Buddhism. Economically, subsistence production was still maintained, with some commercial activities on cultivation of tea, cotton, corn and livestock. For communicative behavior, the villagers exchanged their opinions and were interested in agricultural and vocational training. Radio was the medium that gave the villagers the most access to information. However, other types of media had not attracted their interest due to lack of understanding.