Teachers in Dutch mainstream secondary education are faced with a complex challenge to tailor their instruction to an increasingly diverse student population while at the same time having to meet national and school quality standards. Consequently, this demands a high degree of adaptability of teachers though they do not always feel capable to address their students’ learning needs. The Japanese professional development approach Lesson Study may address this given its distinct focus on student learning. In a Lesson Study cycle, small groups of teachers systematically prepare, teach and observe, evaluate, and refine so-called research lessons. Despite rapidly growing research evidence in the context of Lesson Study, only limited studies focu...