This three-year project will continue documentation and description of the Arawan, Muran, and Chapakuran families, spoken in the states of Amazonas and Rondonia in Western Brazil. This effort wi11 result in full grammars (dictionaries, phonetics, phonology, morphology, and syntax) of Suruwaha (the only Arawan language yet undescribed; spoken by 100-200 people in the state of Amazonas, Brazil); 'Oro Win (a dying Chapakuran language spoken by only five people (all over forty years of age) in Western Rondonia); and Piraha (spoken by approximately 200 people in Amazonas). This study will also include the first systematic linguistic survey of Mura, a language closely related to Piraha, to verify whether or not anyone still speaks this language, previously documented only by word lists collected by explorers in the 19th and early 20th century. The project will result in several theoretically and typologically oriented articles on aspects of the phonetics, phonology, morphosyntax, and semantics of these languages - all three of these families are known for their unusual typological characteristics (phonological and morphosyntactic, described in the project description). The research is significant because it provides a basis for future theoretical, typological, and historical-comparative studies of these otherwise nearly unknown families and because it directly tests several hypotheses relevant to current phonological and syntactic theory.