The paper is aimed at discussing the contribution of cognitive science and the learning sciences to Japanese education. First, the authors describe the emergence of a new educational discipline, the learning sciences, and its methodological approach to educational practice called the design-based research. In particular, the emphasis is placed on how unique the methodology is by explaining the progressive refinement of classroom practices based on design principles. Secondary, the author's design-based research project is given as an example of how the learning sciences contributes to the classroom practice in Japan. Furthermore, the design-based research is discussed as a new systemic program for teacher education. Finally, the authors propose an approach to new educational reform based on evidence from the learning sciences research.