Grouping students homogeneously by ability level is a common practice in public middle and secondary schools. This practice persists despite research evidence that it actively hinders students' learning. To change grouping practices, however, concurrent changes must be made in the design of schedules, curriculum, and instruction. Such changes can be made in ways compatible with many effective teaching and learning practices that characterize the middle school. In fact, there are many small, concrete, and mechanical things that middle-level educators can do to create an environment that communicates to students the idea that learning is the most important thing in the school setting. Of numerous research findings and practical considerations related to heterogeneous grouping, none is more important than the fact that all students learn best in classes where the ability level is average or higher. This is the starting point for changing attitudes and practices. The time has come to close the door on homogeneous grouping at the middle level. (RH)