This chapter provides a comprehensive analysis of phrase structures in the Thai language, focusing on how different types of phrases contribute to sentence construction and meaning. The chapter begins by reviewing multiple classification systems, ranging from traditional models that categorize phrases by word class to modern linguistic frameworks that emphasize syntactic functions. Key phrase types discussed include noun phrases, quantity phrases, verb phrases, prepositional phrases, and adverbial phrases. Each section explores the internal structure of these phrases, including heads, modifiers, and complements, and illustrates their roles within Thai syntax through a wide array of examples. The chapter also delves into complex constructions such as noun groups, phrasal verbs, preverbal auxiliaries, and subordinate clause modifiers, highlighting the fluidity and precision of Thai phrase formation. By combining theoretical perspectives with practical examples, this chapter equips readers with a deeper understanding of how phrases function as foundational elements in Thai grammar and communication.