1. Introduction Magdelene Lampert; Part I. Focusing on Doing and Learning Mathematical Talk: 2. Language socialization in the mathematics classroom: discourse practices and mathematical thinking Mary Catherine O'Connor; 3. The role of imagery and discourse in supporting students' mathematical development May McLain; 4. Building a context for mathematical discussion Paul Cobb; 5. Disciplined perception: learning to see in technoscience Rodney McNair; Part II. Focusing on Teaching Mathematical Talk; 6. Investigating teaching practice Reed Stevens; 7. The teacher's role in mathematical conversation: stepping in and stepping out Rogers Hall; 8. Teacher talk about how to talk in small groups Peggy Rittenhouse; 9. Teaching and learning politeness during mathematical argument in school Merrie Blunk; 10. Afterword: closing reflections on mathematical talk and mathematics teaching Perri Weingrad.