A finely balanced linguistic ecology is needed to sustain the practice of linguistic exogamy which ensures that marriage occurs between speakers of different languages. These linguistic ecologies and the languages used to sustain them can begin to breakdown as speakers transition to larger world languages. Siriano and Desano, two languages of Northeastern Amazonia, have traditionally been maintained through linguistic exogamic practices which are now breaking down with the increasing influence of Brazilian Portuguese and Spanish. Wilson Silva of the Rochester Institute of Technology will undertake a three-year study of Siriano [sir] and Desano [des] before further influence of language contact makes this difficult. These languages exhibit a number of typologically noteworthy features of broad scholarly interest such nasal harmony (where nasality extends over several segments), tone (the use of pitch for meaningful contrasts), noun classifiers (classifying nouns grammatically in terms of universal semantic parameters), and evidentiality (indicating what kinds of evidence are available for a given statement). Research products will include a linguistically annotated database, a reference grammar for Desano, audio and video documentation and preliminary description of Siriano. Silva's research will be useful in reconstructing the genetic relationship among languages of the Vaup�s Linguistic Area to which Desano and Siriano belong. Understanding the structures of these closely related languages of the Eastern Tukanoan branch of the Tukanoan family will shed light on the nature of language change through contact with other languages. This project has strong support from the communities and their leaders, and involves close collaboration between researchers and community members in Colombia and Brazil where these languages are spoken. The corpus of audiovisual and audio recordings collected as a result of this research will be archived at the Archive of the Indigenous Language of Latin America at the University of Texas at Austin and at the Museum of the Indian at National Foundation of the Indian (Museu do �ndio at the Funda��o Nacional do �ndio), Brazil.