In this chapter, we will discuss opportunities for teacher conversations in lesson study to establish a more solid foundation for decision-making and strengthening knowledge development. Through theory and practical examples we will first identify how conversations can contribute to bringing up diverse kinds of knowledge relevant for specific cases and second, how certain characteristics of teacher conversations can either increase or inhibit opportunities for knowledge development. A main goal for this chapter is to provide ideas about how to assess the kinds of talk that go on in lesson study groups. This is essential for groups that wish to develop their dialogic approach to knowledge development.