Acehnese is an Austronesian language spoken by some two and a half million people in the Province of Aceh in northern Sumatra, Indonesia Acehnese used to be a field of study during the Dutch rule in the nineteenth and early twentieth centuries, although no complete grammar of Acehnese was ever written. Since then, Acehnese has been a nearly unknown language to linguists. The interest of modern linguists outside Indonesia in this language grew following Lawler's two articles (1975 & 1977). The most important work by a western linguist is Durie's (1985) dissertation, which deals mostly with the phonology and the morphology of the language. Much of the syntax, especially complex sentences, has not yet been fully described. The present study is an attempt to treat this part of Acehnese grammar, with the focus on complementation and relativization, which are treated in chapters 5 and 6. The three preceding chapters are also important for a full understanding of complex sentences. They are Chapter 2, on the derivation of four major classes of words, Chapter 3, on sentences, and Chapter 4, on the agreement system The four classes of words discussed here are nouns, verbs, adjectives, and adverbs. The distinction between verbs and adjectives is important for the discussion on the agreement system. The nouns section contains a subsection that discusses the full and bound forms of pronouns, which are used as agreement clitics. Chapter 3 has three important sections, dealing respectively with word order, intonation, and basic sentence structure. Chapter 4 is a complete treatment of the complex agreement system in Acehnese. The data were recorded during six month's research in North Aceh. They consist of conversations and stories. The method used is mainly descriptive. The purpose is to describe the various forms of complex sentences and the context in which each variant is used. Some of the phenomena in Acehnese have no grammatical explanation; they can only be explained in terms of context.