This Chapter provides a comprehensive examination of Thai phonology and pronunciation, foundational elements in mastering the Thai language. The chapter begins with an overview of the Thai phonological system, emphasizing its tonal nature and the critical role of pitch in distinguishing lexical meanings. It explores the five distinct tones in Thai—mid, low, high-falling, high, and low-rising—and illustrates their function through detailed tonal analysis and practical examples. The chapter further addresses the complexities of Thai consonants, vowels, clusters, and diphthongs, including their phonetic transcription, tonal implications, and variable pronunciation patterns shaped by loanwords and silent characters. Special attention is given to intonation and stress, which, although subtler than in non-tonal languages, significantly affect sentence rhythm, meaning, and emphasis. Through in-depth discussion of tone boxes, pronunciation principles, and stress at both word and sentence levels, the chapter equips readers with analytical tools and applied strategies for effective spoken communication in Thai.