Typical goals for inquiry-oriented mathematics classrooms are for students to explain their reasoning and to make sense of others' reasoning. In this paper we offer a framework for interpreting ways in which engaging in the reasoning of someone else is productive for the person who is listening. The framework, which captures the relationship between engaging with another's reasoning, decentering, elaborating justifications, and refining/enriching conceptions, is the result of analysis of 10 individual problem-solving interviews with 10 mathematics education graduate students enrolled in a mathematics content course on chaos and fractals. The theoretical grounding for this work is that of the emergent perspective (Cobb & Yackel, 1996).