This study presents an acoustic analysis of three sentence types in Thai (declarative, interrogative, and emphatic) with the goal of providing a basic characterization of their prosody. To investigate prosodic realizations of sentence final syllables, we placed, in a sentence-final position, a target word which varied in one of the 5 lexical tones in Thai. We also varied the tonal context before the target word so that the pre-target word ends with low (21), mid (31), or high (45) tones. Preliminary results from one speaker show that F0 measures, especially f0 maximum, minimum, and range, differed across sentence types. In particular, emphatic sentences were distinguished from non-emphatic sentences by expanded F0 range, whereas target words in questions were distinguished from those in declarative sentences by both higher F0 maximum and minimum. Syllable duration also played a role in signaling emphasis and question: emphatic sentences were significantly longer than non-emphatic sentences, and questions were significantly shorter than declarative sentences. Interestingly, the tonal pattern of the target word changed for the case of emphasis when the target word had 31 and 45 tones. We will present findings from four additional Thai speakers and discuss their relevance to the intonational phonology of Thai.