Listening to students' mathematical thinking is one of the trademarks of reform-minded visions of mathematics teaching. The questions of when, where, how, and what might help prospective teachers learn to do so, however, remain open. This study examines how a mathematics letter exchange with Grade 4 students provided an occasion for prospective teachers to learn about students' mathematical thinking and to examine their interpretive practices. Analysis of the interactions between students and prospective teachers, and of the reflective writing of the latter, revealed changes in the patterns of their interpretations. I characterized these as changes in the focus of interpretation, from correctness to meaning, and in the interpretive approach, from quick and conclusive to thoughtful and tentative. I also discuss factors associated with these interpretive turns. The idea of teachers listening to and understanding students' thinking has been widely promoted and supported in the education community. In the Professional Standards (National Council of Teachers of Mathematics (NCTM), 1991), the analysis of students' thinking is highlighted as one of the central tasks of mathematics teaching. In this report, the analysis of students' thinking is seen as a resource that can help teachers make informed decisions in their classrooms and improve their practice. Such a listening orientation towards teaching promotes a learning environment conducive to and respectful of students' own sense making and intellectual autonomy (Davis, 1996; Kamii, 1989). In contrast, when teachers do not listen to or do not understand their students' thinking they tend to dismiss it by imposing their own formalized constructions onto the students (Cobb, 1988; Maher & Davis, 1990). Although there are various ways in which teachers can listen to their students' mathematical ideas, Davis (1996) reminded us that not all forms of listening are conducive and respectful of students' thinking. He discussed three different orientations teachers might have towards listening in the mathematics classroom. Teachers with an evaluative orientation, according to Davis, tend to listen to students' ideas in order to diagnose and correct their mathematical misunderstandings. Teachers with an inter- pretive orientation, on the other hand, listen to students' ideas with the