A case study was conducted by employing exploratory sequential design of the mixed methods design to understand the progress and effectiveness of the government’s scaling up process of the lesson study approach in Zambia, which started in a few pilot provinces and then moved to the non-pilot provinces. The major objectives of the study were to understand how the benefits of the scaling up of lesson study have reached school management and teachers; how the concept and method of lesson study and student-centred learning are understood, interpreted and practised by teachers in the non-pilot provinces; how the cognitive and non-cognitive developments of the students are observed in the classrooms; and to identify inhibiting factors in realizing an inclusive, quality education in the process of scaling up the use of lesson study. The findings of the study indicated that lesson study activities were conducted in schools because they had to follow the government policy in one of the non-pilot provinces, Lusaka Province of Zambia. However, the concept and/or methods of the lesson study were not properly understood or practised by the teachers. This paper suggests that to realize the substantial scaling up of the lesson study, not only policy dissemination or cascade-type training, but also school-based training and follow-up for teachers need to be conducted and strengthened, and headteachers and local education officers should provide teachers with the necessary skills and resources.