Despite nonnative English-speaking teachers' (NNESTs) professional qualifications and increasing contributions to research in TESOL, the native speaker (NS) myth (Phillipson, 1992) continues to undermine these teachers' sense of professional legitimacy and pedagogical efficacy. Thus, due in great part to the notion of an idealized NS teacher of ESL (Leung, Harris, & Rampton, 1997) that circulates within various professional discourses, many skilled NNESTs struggle to form a professional identity as legitimate TESOL professionals in the contexts where they teach (Canagarajah, 1999), since NS status permanently eludes them. In light of this challenge, making sure that NNESTs are supported in developing and asserting a professional identity is a key concern in second language teacher education. The present, ethnographically-oriented study argues that participation in "dialogic narrative inquiry" as a form of professional development can support NNESTs in their efforts to claim professional authority vis-a-vis the NS myth and ideology. Specifically, it explores how a focus on NNEST-related issues provided useful resources to participants (teaching assistants in the ESL program of a large American university) as they challenged the NS myth, while conceiving of, articulating, and internalizing alternative ESL teacher identities with which to (re)position themselves as legitimate language professionals. This interventional focus, implemented through participation in online group discussions and via a dialogic blog with the researcher, as well as through engagement with an instructional curriculum addressing NNEST issues, served as mediational means for the teachers to reconceptualize their instructional practices, and influenced the way in which their very students (undergraduate-level ESL learners) came to think of themselves as English speakers and users. Data excerpts from a variety of sources, including online discussions, dialogic blogs, classroom observations, stimulated recall sessions, teacher interviews, and students' writing, are used to illustrate the findings. The overall theoretical framework for this project is Vygotskian sociocultural theory, complemented by a grounded content analysis based on the principles of ethnographic semantics (Spradley, 1979; Spradley & McCurdy, 1972) and on the constant comparative method (Bogdan & Biklen, 1998; Glaser & Strauss, 1967; Goetz & LeCompte, 1981). An additional key concept for the analysis is the "indexicality principle" (Bucholtz & Hall, 2005), which stresses the discursive nature of identity negotiation and realization. The final themes that emerged from the data analysis reflect evidence of the participants' emerging understanding of: (a) the NS/NNS dichotomy, (b) the NS myth, (c) their self-concept and identity(-ies), (d) their self-confidence as ESL teachers, (e) their perceived English skills/expertise, and (f) their perceptions of (critical) pedagogy. The study concludes by offering implications for the professional development of pre- and in-service NNESTs in the field of TESOL teacher education. [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.]