Shrinking the achievement gap in mathematics is a tall order. One way to approach this challenge is to think about how the achievement gap manifests itself in the classroom and take concrete action. For example, opportunities to participate in activities that involve mathematical reasoning and argumentation in a safe and supportive manner are central to the development of mathematical competence and identity. It follows that one way to think about equity in the classroom is to consider the kinds of opportunities created for different groups of students to participate in these activities (NCTM 2000). In this article, the authors describe three strategies that can help narrow classroom participation gaps--that is, differences in the types and rates of participation among groups of students from dominant versus non-dominant ethnic, racial, socioeconomic, or linguistic backgrounds in mathematics classrooms. These strategies are the result of ten years of researching successful mathematics teachers, the experience teaching middle school and high school mathematics in demographically diverse classrooms, and new theories of mathematics learning that take into account identity, culture, and power in the mathematics classroom. The authors end each section by noting tensions that teachers have faced in attempting to broaden participation in their classrooms.