This study draws from a cultural-historical perspective to explore the experiences of two pre-­service ESL teachers in terms of their efforts to maximize the use of the target language during a school practicum. Both student teachers were fluent in English, had received training in maximizing target language use during their university studies, and were keen to implement this goal during their practicum. Through contrasting case studies, the study illuminates how aspects of their respective activity settings variously facilitated or constrained their ability to do so. Amongst the findings, the study demonstrates how the power wielded by the cooperating teacher was exercised through the choice of both symbolic and pedagogical tools (Smagorinsky et al., 2004). The study also highlights how the socio-political context in which the study took place mediated students' willingness to use the target language.