This thesis examines modern politics in Thailand, its policy, and its search for national security, by showing the impact of the United States on Thai politics. The thesis maintains that politics in Thailand are results that come from attempts of the Thai government to adapt to American involvement in Thailand. The thesis describes the Thai government scene from 1945 to 1972. It analyzes the elements of American involvement and factors in Thai society that are pressured by this involvement. The attempts of the Thai government and its politicians to bring their policy more into line with the changing situations are shown in their reactions to problems of Southeast Asia--the focus of which is on the problems of Vietnam, the problems of China, and the withdrawal of the U.S. to a profile of low visibility.