The Warihio language is a member of the Uto-Aztecan family. The language consists of two dialects: the Upland Warihio in the mountains of Chihuahua and the River Warihio along the Mayo River in Sonora, Mexico. With the various Tarahumara dialects, and Yaqui and Mayo languages, it makes up the Taracahitic sub-group of the Sonoran branch of the Uto-Aztecan family of languages. All of the field and supporting data for this work comes from the River dialect. This work deals with all of the major linguistic aspects of the River Warihio language, including a brief description of its phonology, major and minor word classes, noun phrase, relative clauses, simple sentence structure, negation, voice, and complex sentences structure. Likewise, a short comparative section within Uto-Aztecan languages of some relevant aspects of the Warihio grammar. Also included is a basic Warihio-English-Spanish dictionary and several analyzed texts. These appendixes provide natural language data for study of areas not covered in detail here. Chapter one provides information regarding ethnographical aspects of the Warihio people; it also establishes the phonemic inventory of the language and the notational system used through the dissertation. In chapter one I also propose a stress pattern based in the information about possible combination of roots and affixes allowed in the language. The main theorethical-typological contributions that the study of Warihio might provide are contained in the following chapters: Chapter 5: Simple sentence. Flexibility in order constituent displayed by Warihio texts and its relation with the focus phenomena are described in this chapter. Coding and control properties as well as participants behaviour are also described here. Chapter 7: Voice. I have integrated different voice phenomena such as passive, causative, reflexive, applicative, external possession, and ethical dative in a general semantic frame of voice. I describe typologically interesting findings in the passive and causative constructions. River Warihio has some interesting contrasting aspects within Uto-Aztecan family and morpho-syntactic features that are relevant theoretico-typologically. Its flexible pragmatically motivated constituent order altogether with the lack of coding properties for grammatical relations make Warihio an unusual language within Uto-Aztecan family and cross-linguistically as well.