Relying on the framework of communities of practice and using qualitative case study methods, this study investigated three ESOL teacher candidates' identity negotiation as they learned to work with English language learners through coursework and internship experiences in a 13-month MATESOL program. The findings pointed out that the participants negotiated their emerging teacher identities through teacher education courses and internship in three main ways: (a) they negotiated who they aspire to become as an ESOL practitioner as they set and revised their priorities in serving ELLs, (b) they roadtested their imagined identities through guided reflective practices embedded in the teacher education program provisions, and (c) they acquired the professional discourse which helps them make sense of and engage in the practices of the community of ESOL teachers. This study contributes to the growing research on language teacher identity by illuminating the intertwined nature of teacher learning and identity in shaping the contours of teacher identity negotiation. The study implicates that teacher education should incorporate teacher identity as an explicit goal that serves as an interpretive frame for teacher candidates' ongoing professional learning and growth as practitioners.