This study aims to explore the role of school-based practicum in promoting pre-service English language teachers' professional development through the use of a longitudinal design in combination with qualitative methods. To achieve this aim, pre-service teachers were asked to successively reflect on video-recordings of their micro-lessons in their university-based methodology courses directly after delivering the micro-lessons and retrospectively after their practicum experience. The participants of this study were 13 pre-service English language teachers studying at a foundation university in Istanbul, Turkey. The same data collection methodology was adapted before and after the practicum to gain a deeper understanding of the learning stemming from school-based practicum. The data for the study came from pre- and post-self-evaluation reports as well as pre- and post-focus-group interviews that had been collected based on the pre-service teachers' video-recorded microteaching simulations. The findings indicate that pre-service teachers commented on the same pedagogical, psychological, and physical factors they had noticed regarding their micro-lesson before and after the practicum. However, some qualitative changes were detected in their views over time as they had become more learner-oriented and had developed a more reflective view of teaching following the practicum. These findings have implications for the impact of practicum for future teacher education programs.