This dissertation constitutes the first attempt at describing the grammar of Wampis (Spanish: Huambisa), a language spoken in the Peruvian Amazon. Wampis belongs to the so-called Jivaroan family of languages and is closely related to sister languages Awajun, Shuar, Shiwiar and Achuar. The grammar introduces the Wampis people and some aspects of their culture and history before analyzing the major aspects of the language from a grammatical perspective. Wampis possesses a complex prosodic system that mixes features of tone and stress. Vowel elision processes pervade most morphophonological processes. Nasalization is also present and spreads rightward and leftward through continuants and vowels. Every word in Wampis needs at least one high tone, but more can occur in a word. Morphologically, Wampis is a very rich language. Nouns and especially verbs have very robust morphology. Affixes and enclitics contribute different meanings to words. Some morphemes codify semantic categories that are not grammatically codified in many other languages, such as sudden realization, apprehensive and mirative modalities. An outstanding feature of Wampis is the pattern of argument indexation on the verb, which follows an uncommon pattern in which the verb agrees with the object (and not with the subject) if the object is a Plural Speech Act participant. Parallel to this pattern of argument indexation is the typologically uncommon pattern of object marking in Wampis, whereby a third person object noun phrase is not marked as an object if the subject is a first plural, second singular or second plural person. Wampis exhibits a nominative-accusative alignment. All notional objects (direct, indirect, object of applicative) are treated identically in the syntax. The preferred order is A P V. Wampis also possesses a sophisticated system of participant tracking, which is instantiated in the grammar via switch-reference markers. Another typologically uncommon feature of Wampis is the presence of a sub-system of switch-reference markers that track a participant that is not a subject. Throughout the twenty-one chapters of this grammar, other issues of Wampis related to different areas of phonology, morphology and syntax are also addressed and described from a functional and a typological perspective.