As many as 20 million Americans claim to be of Scottish or Scots/Irish descent. One of the primary heritage languages of this community is Scottish Gaelic. This language is the medium for a rich culture of literature, song, poetry, history and indigenous knowledge-systems. It also provides an important window into the world-view and culture of the ancestors of the Scottish-American community. Sadly, the Scottish Gaelic language is severely endangered. There are no monolingual speakers and, in Scotland, the number of speakers who use the language everyday has dropped more than a third in the past 30 years. At this rate, the language will no longer be viable within a generation. The potential loss to our understanding of the culture and background of so many Scots and Scottish Americans is of great concern. The Scottish Gaelic language is also of interest to linguists who study the structure of language. The sound system of Gaelic is very different from that of English. It has particular sounds and patterns of sound combinations that are rare or unique in the world's languages. Because linguists seek to understand the fundamental patterns that hold of languages in general it is necessary to look to languages like Scottish Gaelic. The interests of Scottish Gaelic speakers and scientific linguists intersect in this domain. In order for linguists to properly understand the sound system of a language, they have to use instrumental measures of how speakers articulate sounds and use psycholinguistic experiments to measure how speakers understand and use the patterns of sounds. The patterns in commonly spoken languages like English and Spanish has been relatively well studied but the sound systems of lesser spoken languages with rare sounds, such as Gaelic, are less often addressed. On the other side of the coin, for the speakers of the language, one of the first steps towards building a stable linguistic community is to develop language teaching materials in and about the language for use by the community, both in the USA and in Scotland. Using modern linguistic instrumental and psycholinguistic techniques. Profs. Andrew Carnie, Mike Hammond, Diana Archangeli and Natasha Warner along with Scottish Gaelic native speaker Muriel Fisher will investigate the articulation, patterning and perception of certain unique properties of the Gaelic sound system. For example, using an ultrasound placed under the chin, they will measure the position of the tongue during the pronunciation of certain consonants and vowels. Similarly, they will ask speakers to speak while wearing a special mask that measures how much air is coming through their nose and mouth. The output of this research will be a description of the Gaelic sounds structures which will help complete an on-going description of the language. In addition, in doing this research graduate students will be trained in the techniques of sound analysis of an endangered language. This training will allow the students to do similar work on other endangered heritage languages. This work has important implications for documenting and preserving the linguistic traditions of the Scottish and Scottish-American communities.