The goal of those who support NCTM's Curriculum and Evaluation Standards for School Mathematics (1989) is to develop the mathematical power of all students. To achieve this goal, teachers in all mathematics classrooms will need materials and professional support to maintain their commitment to the task and their proficiency in accomplishing it. “Teachers are key figure in changing the ways in which mathematics is taught and learned in schools. Such changes require that teachers have long-term support and adequate resources” (NCTM 1991, 2). This focus issue contains a variety of ideas to support classroom teachers as they begin the difficult job of planning for instruction in mathematics that will help all students achieve mathematical power.