In recent years, a growing interest has developed in lesson study, a Japanese form of professional development that centers on teachers coming together to examine their practice by planning and trying out lessons. This article examines the lesson study work of a group of elementary mathematics teachers to speculate about the educative value of lesson study. Specifically, this article explores whether lesson study can afford teachers opportunities to learn about mathematics in a way that is useful for the enactment of reform-minded teaching. What hinders teachers in taking advantage of such opportunities and how such obstacles can be overcome are also addressed. Implications for future research on lesson study and for our broader understanding of what teachers learn from examinations of practice are discussed.