Since the language used by people has the potential to signal a membership in a discourse community, it is significant that prospective teachers speak the appropriate social language to be able to claim a strong membership in the community of teachers. This qualitative study explores a group of pre-service teachers' professional language use and their claims for membership in the teaching profession. In this study, a scrutiny of the meanings reflected by 21 pre-service teachers during their one-semester internship is provided to illustrate the extent to which their classroom practice brings about a change in both their professional language use and their recognition of themselves as valid members of the specific discourse community of English as a foreign language (EFL) teachers in Turkey. The methods of data collection in this study consisted of a blend of qualitative techniques: (1) the pre-service teachers' weekly field notes; (2) their weekly reflective reports on their own field notes and their classroom practice experiences; (3) their written responses to open-ended questions posed at the end of the semester; and (4) my observational notes which I took during weekly discussion sessions. Findings underscore that there are several reasons leading to the participants' limited professional language use. A focus on teachers' professional language use--a significant part and indicator of teachers' professional development--might help to reveal the dimensions of the processes involved in teachers' identity formation in different educational contexts as well as in mainstream contexts.