It is the aim of this thesis to study tenses in Thai, attemping especially to determine the number of tenses in the Thai Language, the aspects in each tense, and the expression of each tense. This work is a study of the data collected from everyday conversation of people who use the Bangkok dialect. The thesis shows that there are 3 basic tenses in Thai : Present Tense, Past Tense and Future Tense. The Present Tense must have aspects and may be divided into 5 types: the progressive Present, the frequentative Present, the continuative Present, the simulfactive progressive Present and the simulfactive frequentative Present. The Past Tense may be divided into the Past Tense with no aspects and the Past Tense with aspects. The Past Tense with aspects may be further divided into 5 types: the progressive Past, the simulfactive Past, the frequentative Past, the simulfative progressive Past and the simulfactive frequentative Past. The Future Tense may be divided into the Future Tense with no aspects and the Future Tenes with aspects. The Future Tense with aspects may be further divided into 5 types: the progressive Future, the completive Future, the simulfactive Future, the frequentative Future and the simulfactive progressive Future. Tenses in Thai may be expressed by a verb in combination with words of other classes except in the case of the progressive Present, the frequentative Present and the Past Tense with no aspects which may be expressed by a verb alone or by a verb in combination with words of other classes. The thesis is divided into 8 chapters. The first chapter is an introduction stating the scope and purpose of the thesis. The second chapter deals with word classes relevant to the expression of tenses in the Thai language. The third chapter deals with the definition and the classification of the tenses and their aspects. The forth chapter deals with the expressions of the Present Tense. The fifth chapter deals with the expressions of the Past Tense. The sixth chapter deals with the expressions of the Future Tense. The seventh chapter deals with the temporal phrases which express the tenses and the frequentative aspect. The last chapter is a conclusion. In it, it is suggested that further research should be undertaken on sentences in which more than one tense appears.
