This study investigated the intelligibility of Chinese graduate students to their Indian, Chinese, Korean, and American peers. Specifically, the researcher sought to determine the teaching priorities for English for Academic Purposes in the US, where listeners have a wide variety of native languages. Research on Second Language Acquisition (SLA), International Teaching Assistants, and English as a Lingua Franca (ELF) has not provided sufficient empirical data on the factors that affect intelligible English communication among academic professionals with many native languages (L1). SLA has focused on the processes and factors affecting the acquisition of second language (L2) phonology; and ITA research has focused on the communication needs of international graduate students teaching American undergraduates. Both perspectives examine the intelligibility of foreign-accented speech to native English-speaking listeners. World Englishes (WE) and ELF argue for more research from the perspective of L2 listeners, which thus far has largely been limited to linguistic descriptions and case studies. A psycholinguistic word-recognition-in-noise study was designed to examine to what extent a talker's L1 and segmental pronunciation accuracy affected intelligibility, and how this varied by a listener's L1 and word familiarity. Participants included 6 male graduate students (Chinese & American) as talkers and 72 graduate students (Indian, Chinese, Korean, & American) as listeners. The oral English proficiency level of the international participants was held constant at "graduate TA certification" and all American listeners were natives of Ohio. Talkers were recorded reading 60 sentences from the Bamford-Kowal-Bench Standard Sentence Lists, revised for American English. The stimuli were mixed with white noise at a +5 dB signal-to-noise ratio and presented in a counterbalanced design to listeners, who transcribed the sentences they heard. Intelligibility was calculated using a dichotomous measure of key word transcription accuracy. A series of logistic regression mixed-effects models revealed that talker L1, listener L1, and word familiarity were significant predictors of intelligibility. Talker segmental accuracy did not significantly predict intelligibility. American English L1 talkers were more intelligible than Mandarin L1 talkers to all listeners, except to Mandarin L1 listeners, who found them equally intelligible. This is an important finding for English Language Teaching, since most teachers are either native speakers of English or share the L1 of their students. Special effort must be made to include more diversity of accents in the audio and video materials for international students preparing to study or conduct research in English L1 countries. English for Academic Purposes curricula cannot assume that one size fits all of the diverse listeners encountered in the academic context. As the findings indicated, intelligibility improved as listener word familiarity increased, and was also affected differently according to the listener's L1. Consequently, in the academic setting more attention should be paid to increasing listeners' discipline-specific vocabulary, which would benefit both international and American listeners. More attention should also be paid to providing both international and American university students with the linguistic training necessary to accommodate the range of accent diversity that has become a reality in higher education today. [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.]