This research is designed to provide the basic social and economic data of the Karen hilltribes in Ban Phra Baht Huay Tom, Tambon Na Sai, Amphoe Lee, Lamphun province. It was collected through a questionnaire about the population and economy during December 1979 and January 1980. It is found that according to the social condition in Ban Phra Baht Huay Tom, the administration depends on the government, but there is a leader of the village who is the most senior. The Karen communities are bound to Buddhism because they worship Kru Ba Wong who mainly helps community developing, i.e. in education and occupation and he is a facilitator who helps to control the internal order in the community with principles in Buddhism. Because of the setting up of a school in the village and the help of Hilltribe Development and Welfare Center, the people in the village are more literate. According to the economic conditions, agriculture is the main occupation of the Karen. They grow rye and transplant rice. Even though, they do not receive as much income as they do as labourers which is the main occupation of some and the additional occupation of others. Most of the households grow vegetables and fruits to mainly consume within their households. Because the Karen in Ban Phra Baht Huay Tom are vegetarian, they do not farm for consumption and commerce. They only farm cattle and elephants for their labour. Since 1978, the Hilltribe Development and Welfare Center has helped to develop the economy such as increasing the products, growing plants for soil maintenance, improvement of the plants, development of sources of water and setting up the rice bank. Furthermore, they also support the social development through educational development, occupation training, leader of the village training, setting up the village committee as well as public health development. The center has set the priority of social and economic development which mainly depend on the community needs and problems.