In this presentation, key teacher and student learning from an ongoing interdepartmental collaborative lesson research (CLR) project in a Japanese university is explained. Our project’s AY2021-2 theme was the implementation of Active Learning approaches to lead EFL students to develop a clearer understanding of course material in their content-based English and English-medium subject courses. The strengths of CLR in this context are highlighted, and suggestions are made for developing similar projects in other contexts.