There are abundant studies on second/foreign language learners' identities. However, there appears to be insufficient longitudinal research on the construction of learners' L2 identities in systematic interactions between fixed dyads in an out-of-class context. Adopting a critical discourse analysis framework (Fairclough, 2003) and suitably informed by discourse theory (Philips & Jogensen, 2002), this article explores how Chinese college students discursively constructed English learner identities in and through processes of interaction and how English learner and user identity and learner language use were mutually constructed. Learners were found to exercise their own agency to establish multiple and changing identities. Such learner identities were found to be constructed through discursive strategies that established oppositions and differences and sometimes were crafted "in situ" to fit the contours of the interactive setting. This article begins with a discussion of the constructs that guide the study and then provides an interpretation of interactional, interview and diary texts that takes account of the sociocultural context from which these were generated. (Contains 1 table, 1 figure, 8 excerpts, and 1 footnote.)