This thesis is the first comprehensive reference grammar of Kilen, a lesser known and little studied language of the Tungusic Family. At present, Kilen is a moribund language with less than 10 bilingual speakers in the eastern part of Heilongjiang Province of P.R.China. Since the language does not have a writing system, the examples are provided in IPA transcription with morpheme tagging. This thesis is divided into eight chapters. Chapter 1 states the background information of Kilen language in terms of Ethnology, Migration and Language Contact. Beginning from Chapter 2, the language is described in the aspects of Phonology, Morphology and Syntax. This thesis is mainly concerned with morphosyntactic aspects of Kilen. Chapters 6-8 provide a portrait of Kilen syntactic organization. The sources for this description include the work of You Zhixian (1989), which documents oral literature originally recorded by You himself, a fluent Kilen native speaker; example sentences drawn from previous linguistic descriptions, mainly those of An (1985) and You & Fu (1987); author’s field records and personal consultation data recorded and transcribed by the author and Wu Mingxiang, one of the last fluent native speakers. The aim is to provide a portrait of a Chinese Tungusic language on the brink of extinction. This thesis does not adopt any particular syntactic theoretical framework. The terminology in this thesis is tended to be theory-free and descriptive. / published_or_final_version / Linguistics / Doctoral / Doctor of Philosophy