This study attempts to further our understanding of linguistic politeness by focusing on both a Western and a non-Western language. It is based on two sets of data (one spontaneous and the other elicited) and provides a comparative analysis of three expressive speech acts produced by native speakers of British English and Thai. At face value, compliments, apologies and thanks may seem to have little referential meaning, yet these speech acts can be crucially important in originating, maintaining or even terminating social relationships. The data reveal a tendency for the two groups of speakers to use the three politeness devices in a different manner, reflecting cross-cultural differences in social norms and value systems. This project follows earlier studies of similar nature, in particular those carried out on different varieties of English. The findings are interpreted within pragmatic and sociolinguistic theoretical frameworks, and are discussed in the following format: linguistic structures of the speech acts, their functions, the topics of compliments, apologies and thanks, interpersonal and contextual factors influencing the production of these expressives, and the responses given to them. The analysis has implications for language specialists and lay people alike, in that it brings together a number of important insights with regard to these speech features that may result in miscommunication if and when British and Thai speakers converse in intercultural situations.