The article focused on factors contributing to socio-cultural changes due to state development policies, investors and other external agencies or groups of individuals. The development results had affected the Thin ethnic communities at Nam So and Nam Pho villages in Tambon Lae; Nam Phi village in Tambon Thung Chang, Thung Chang district; and Pa Kam village in Tambon Bo Klua, Bo Klua sub-district. These changes had affected the ethnic lifestyles. For instance, the ethnic group was promoted to be involved in wet-rice cultivation, which is a low-lying Thai practice, instead of their highland rice cultivation practice. This change had made some highland rice cultivation rituals altered and some had even disappeared. The commercial crop agricultural development by the Agricultural Cooperatives had promoted the borrowing of seeds, fertilizers and pesticides, replacing traditional subsistence agriculture with commercial crop cultivation.