Instruction that meaningfully incorporates students' mathematical thinking is widely valued within the mathematics education community (NCTM 2000; Sherin, Louis, and Mendez 2000; Stein et al. 2008). Although being responsive to student thinking is important, not all student thinking has the same potential to support mathematical learning. Thus, teachers must make choices about which student contributions should or should not be incorporated into the whole-class discussion. In this article, the authors provide a framework to help teachers make these choices.