This article explores the impact of the teacher on student identities within the English language classroom. Based on an empirical study, the article posits that the teacher can play a significant role in the negotiation, co-construction, and legitimisation of student identities in the language class in a number of ways: by focusing on students as intellectual and cultural resources, by giving primacy to students' "transportable" (as opposed to "discourse" or "situated") identities, by giving students the communicative "tools" (i.e., linguistic, pragmatic, and intercultural competences) in order for them to assert identities as an expression of agency, and by facilitating student participation both inside and outside the language class. It is held that the increased motivation, or "investment" in learning gained through the assertion and legitimisation of identities in the language class can have a positive impact on language learning. Similarly, a recognition of students' need to exercise personal agency in their learning as an expression of their perceived identity can have an impact on motivation.