This dissertation compares the phonetic and phonological features of adult non-speakers' productions of words in an endangered Native American language, Oregon Northern Paiute (also known, and hereafter referred to, as Numu), to productions by fluent speakers. The purpose of this comparison is two-fold. The first purpose is to examine the differences in pronunciation that non-speakers bring to the language, which point to possible directions of future language change in a language that is no longer being learned as a first language by children. Changes brought to the language by second language learners are likely to occur due to transfer effects from English and processes of regularization, but may also occur due to the intensification of socially salient language features, or hypercorrection (see Wolfram, 2002). For this reason, two groups of nonspeakers were included in the study: English speaking members of the community where Numu is spoken (Warm Springs, Oregon) and English speakers from outside the community. It was hypothesized that the latter group would only exhibit transfer effects or regularization, while the Warm Springs group would also exhibit hypercorrection of what they perceive to be salient features of Numu. By comparing the productions of the two non-speaker groups, specific aspects of potential change are identified and classified as transfer, regularization, or hypercorrection. The second purpose of the comparison between speaker and non-speaker productions is to ascertain specific differences in pronunciation that result in perceivably accented speech. This research goal is achieved by examining fluent speakers' reactions to non-speakers' productions. It was hypothesized that not all features unique to non-speaker produced speech would result in a perceivable accent. Learners who wish to improve their pronunciation from the perspective of the Numu community could then focus particularly on the features that do contribute to a noticeable accent. This research makes contributions to our understanding of phonetic and phonological change in endangered language contexts, both from a second language acquisition perspective and a socio-phonetic perspective. The theoretical framework for this research is described in Chapter 1, along with information about Numu and about the Warm Springs community. The second chapter provides a phonetic sketch of Numu based on data from four fluent speakers of the language. This sketch forms the basis for comparison of non-speaker productions in later chapters, but also contributes a phonetic record of several features of Numu for future generations of learners and researchers. Chapter 3 repeats these phonetic measurements for nonspeakers, and also examines a number of phonological features of non-speaker speech, finding that study participants from Warm Springs generally have a production advantage as compared to people from outside the community. It also finds that, in some cases, study participants from Warm Springs produce novel segments that are not present in the fluent speaker input, but that do exist in other geographically close Native American languages. Chapter 4 discusses these findings in terms of the possible changes that adult learners may bring to Numu. These changes are explored with regards to three theoretical proposals of endangered language change, including transfer effects from a dominant language, adoption of universal language features, and hypercorrection of socially salient language features. A fourth mechanism of endangered language change is proposed, based on findings that non-speakers incorporate phonological elements of other Native American languages, of which they are not speakers. Chapter five presents and discusses results from a perception test in which fluent speakers provided ratings for non-speaker productions. These ratings are compared to the non-speaker features present in a given production in order to determine which features are linked to lower ratings. These features are hypothesized to contribute to a perceivable accent in the speech community. Finally, Chapter 6 concludes the dissertation with a discussion of wider implications for endangered language change, as well as implications for the use of electronic media in endangered language learning. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]