This thesis is a study of the impact of United Nations Nonghet Alternative Development project on the cultural change of the Hmong at Koepiou village, Nonghet District, Xiengkhouang province, Lao Peoples Democratic Republic. From the in depth interviews of 152 key informants, it is found that after providing infrastructure and extending agriculture to the villagers, the villagers earn more income and it is supported by socio-economic changes to the village. This has caused changes in the basic structure such as culture, customs and local traditions especially the tradition of dragging the bride, the rituals, dress, housing, public health and education. These are improvement and have led to the successful project to eliminate opium poppy cultivation and deforestation from the village by training, meetings and making study trips out side the villages and the administrative institutions. Furthermore, socialization by the family, friends, occupations and mass media have caused the cultural change and the social organization. Thus, when an organization has been changed, it affects other organizations, especially economic organizations. It causes many Hmong traditions to be changed such as the number of days to celebrate the New Year Festival which is new reduced to 15 days. Many families new become nuclear family. It has also affected the right of election and the economy of the Hmong women.