This study was situated in a field-based teacher education program in Japan for English teachers. The focus was on the thought processes of two pre-service teachers (PSTs). The study draws on the interrelated roles of teacher cognition and dialogic reflections that emerged through interviews as mediated spaces to stimulate reflective pedagogical conceptualizations of the participants during their teaching practicum. In contrast to monologic practices, dialogic practices create a richer and more active teacher learning environment during supervision. Data were gathered in a three-staged interview process conducted by the PSTs’ university-based supervisor (UBS) during their two-week practicum at respective high schools. Qualitative coding methods were used to sort the data through comparative analysis in a three-step coding process. Themes were abstracted from the data to encapsulate and report the PSTs’ self-reflective thought processes. Results showed that the PSTs experienced positive growth in identifying metacognitive strategies for instructing students, but also found a gap between university teacher education coursework and the realities of classroom practice that are underpinned by a traditional educational culture of their field-based schools. Consequently, they had to modify their instruction to fit field-based conservative teaching practices. Implications indicate that a dialogic approach enabled a functionally productive mediated space for the PSTs to enrich their pedagogical conceptualizations of the practicum experience to better inform their practice through participating in professional discourse. Results also significantly served to apprise the UBS of the necessity to improve coursework to better prepare PSTs for their practicum.