This chapter explores the fundamental components of English sentence structure, focusing on clauses and complements. It begins by defining independent and subordinate clauses, explaining how they combine to form complex sentences and outlining the nominal, adjectival, and adverbial functions of subordinate clauses. The chapter then delves into describing clauses and sentences, illustrating how complex sentences are built through embedding and distinguishing between finite and non-finite clauses. Finally, it provides a detailed examination of complements and adjuncts, clarifying their roles in sentence completeness and exploring their interaction with different verb types and sentence structures, including imperative sentences.