Neither experimental nor design research in education is as well developed in Japan as in the United States. Yet Japanese educational practice employs a type of educational research called "lesson study" that is credited for instructional improvements, including the shift from "teaching as telling" to "teaching for understanding" in science and the development of structured problem-solving lessons in mathematics. This chapter examines lesson study as an example of the emerging paradigm of "human science," offering an image of how research and practice can relate in ways that inform practical action and the field of educational research. (Contains 1 figure.)