This article illustrates the use of comparison as an instructional approach that can help students develop and use a variety of problem-solving strategies and approaches in the mathematics classroom. Through comparison of solution strategies, students deliberately consider the similarities and differences among methods and how different strategies can arrive at the same solution. According to NCTM (National Council of Teachers of Mathematics), comparison of strategies can enable students to understand what aspects or features of some strategies make them powerful and efficient while other methods are less so, even if they are easier to understand (NCTM 2000). The importance of comparison for mathematics instruction emerges in international studies of mathematics teachers. Researchers who have evaluated the use of comparison in typical mathematics classrooms in the United States, Japan, and Hong Kong found that expert teachers in all three countries frequently used comparison as a tool for teaching mathematics. The authors discuss a study that illustrates the potential benefits of comparison for students' learning and suggests some concrete ways that teachers can use comparison in mathematics classrooms. Some important features that promoted learning from comparison are presented. (Contains 3 figures.)