The thesis explored the social structure of the So ethnic group at Ban Kok Village, which is based on the belief in ancestors’ spirits. The spirits are believed to give the villagers protection and assistance, and the belief engenders a socialization process which encourages the villagers to conform to social norms. The youths have been imparted with the belief by various social institutions by being made to participate in the annual ritual at the village shrine. The participation perpetuates the belief among the youths, leading to the maintenance of their social structure, traditions and culture. The belief and ritual are an implicit means of controlling social behavior.