Bih is a Chamic (Austronesian) language spoken by approximately 500 people in the Southern highlands of Vietnam. This dissertation is the first descriptive grammar of the language, based on extensive fieldwork and community-based language documentation in Vietnam and written from a functional/typological perspective. The analysis in this work is supported with illustrations drawn mainly from texts, with examples from elicitation when needed as well. In phonology, Bih is the only mainland Chamic language to have retained all four Proto-Chamic presyllablic vowels. As a result, Bih is the only Chamic language having only primary clusters inherited from Proto-Chamic and lacks the secondary clusters created by a reduction of an original disyllable form in Proto-Chamic, which occur in other languages of the family. In addition to the vowels, Bih retains only six out of thirteen Proto-Chamic presyllable consonants, but it retains all main syllable consonants from Proto-Chamic. In addition, all voiced "aspirated" consonants in Proto-Chamic become voiceless in Bih. This phonological change is common throughout coastal Chamic and it is also shared among Bih and other two highland Chamic languages, Chru and Northern Roglai, but not with Ede. In morphological terms, Bih is an isolating language. Words are mostly monosyllabic, although there are a number of disyllable or trisyllable words with the fossilized prefixes pa- or ma- or both. Without inflection on verbs, like other mainland Southeast Asian languages, Bih includes a set of particles functioning as grammatical markers. In fact, many Bih words function as either a full lexical verb or particle depending on their syntactic behaviors. The fundamental mechanisms of Bih syntax are clause-chaining and verb serialization. Most grammatical forms develop from serial verb source constructions. Another feature of great areal typological interest is the topic and focus distinction system of Bih, which, in combination with word order alternations, indicates the discourse status of a referent: whether it is new and/or important in the discourse, or the speaker's evaluation of whether or not a referent is accessible to the mind of the hearer, or whether it contradicts a presupposition or expectation on the part of the hearer or of people in general. Bih has a very interesting obviative-like system, which uses one third person pronoun form to refer to the character whose point of view is being represented and another for all other third persons.