There continues to be significant growth in the development and use of speech--mediated devices and technology products; however, there is no evidence that non-native English speech is used in these devices, despite the fact that English is now spoken by more non-native speakers than native speakers, worldwide. This relative absence of nonnative English speech in devices may be due in part to the costs associated with localizing speech devices, but it may also be attributable to the fact that not enough is known about user performance with accented speech in speech-mediated environments. In the absence of targeted research, developers may be relying on existing studies which focus on perception (impression) of accented speech, as a basis of decision-making. However, perception paints only part of the picture when it comes to understanding how and why people perform in certain ways and in certain environments. Three studies were conducted to answer the following questions: (1) What are the acoustic-phonetic characteristics of negatively- and positively-perceived accented speech? And how are these characteristics related to markers of intelligible speech? (2) How do participants perform on different types of accented-speech tasks? (3) What is the relationship between user perception of accented speech and user performance in response to accented speech? and; (4) How do participants perform on accented speech tasks of varying complexity? Arising out of this research, there are six recommendations for the use of accented speech in speech-mediated devices. Also, the findings of this study raise questions about inherent linguistic stereotypes which impact both our perceptions and our choices about the accents we want to hear on our speech devices. A discussion about if and how these stereotypes can be altered and measured are included. Future research should examine the role of experienced non-native talkers in speech devices. Results of study one demonstrated that some experienced non-native talkers were positively-perceived by raters and may be good candidates for talkers in speech devices. A study like this would explicitly establish if listeners consistently make native vs. non-native distinctions in their preferences or if a prestige continuum emerges. [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.]