The purpose of this dissertation was to investigate the perceptions of preservice teachers toward native and nonnative English speaking (NES and NNES) graduate teaching assistants (GTAs) in English as a second language (ESL) methodology and/or ESL assessment courses at a Southwestern U.S. university. This study also investigated the perceptions of NES and NNES GTAs toward preservice teachers. This study explored the issue of whether preservice teachers are prepared to accept and validate diversity among their instructors which in turn should make them sensitive to diverse learners they will encounter in their future teaching. In the first part of the study, a total of 262 preservice teachers were surveyed. The survey data were collected in spring 2007 and fall 2008. Of the 262 preservice teachers, 20 participated in focus group discussions to provide further insight on their views of NES and NNES GTAs. In the second part of the study, four GTAs participated in a longitudinal study by writing online blog entries after any encounters (positive or negative) they had with their students inside and outside the classroom. The blogs reflected the GTAs? immediate reactions after their classes. In addition, semi-structured interviews were conducted with the GTAs. Findings of the first study revealed that preservice teacher perceived NES and NNES GTAs differently. Preservice teachers put a lot of emphasis on the intelligibility of the NNES GTAs. The preservice teachers were ?tolerant? if their NNES spoke English ?clearly?. However, there were some preservice teachers who were dissatisfied with their NNES GTAs due to their possessing a non-mainstream language. Findings of the second study revealed that NNES GTAs faced major challenges in their effort to be recognized as legitimate and competent instructors. Although the GTAs had vastly different personal backgrounds, perceptions, and identities as instructors, common themes or issues emerged from the data: (1) teaching is complex (linguistic, cultural, and racial issues are involved); (2) beliefs about teaching can change; (3) challenges are faced as an ?outsider? instructor; and (4) teaching provides experiences of joy. The study has implications for teacher education programs and training programs offered for international graduate students by universities.