This article describes the ways in which the mathematics department of an urban, ethnically diverse school brought about high and equitable mathematics achievement. The teachers employed heterogeneous grouping and complex instruction, an approach designed to counter status differ-
ences in classrooms. As part of this approach teachers encouraged multidimensional classrooms, valued the perspectives of different students, and encouraged students to be responsible for each other. The work of students and teachers at Railside School was equitable partly because students achieved more equitable outcomes on tests, but also because students learned to act in more equitable ways in their classrooms. Students learned to appreciate the contributions of students from different cultural groups, genders, and attainment levels, a behavior termed relational equity. This article describes the teaching practices that enabled the department to bring about such important achievements.