Boston University, five school districts in the Greater Boston area (Arlington, Chelsea, Lawrence, Waltham, and Watertown Public Schools) and the Education Development Center, propose to establish Focus on Mathematics, a targeted Math and Science Partnership focusing on mathematics teaching and learning in grades 5-12. The Partnership's approach to increasing student achievement and teacher quality is through three inter-related programs that provide teachers with solid content-based professional development, place students into rigorous courses and curricula, and establish a mathematical community in which mathematicians and precollege educators work together to put mathematics at the core of 5-12 mathematics education. The project features: a research based design that builds on prior work; core involvement of mathematicians; a coherent program of professional development for teachers based in mathematics; a thorough curriculum review; yearly student achievement targets; and the establishment of a lasting mathematical community. The Partnership offers a new professional masters degree for teachers, the Masters in Advanced Study and Teaching: Mathematics degree, and provides a model that supports mathematically active careers in education and exemplars of content-based, teacher-driven professional development programs. Supporting partners include the Center for Industrial Mathematics and Statistics at Worcester Polytechnic Institute and the Department of Mathematical Sciences at the University of Massachusetts at Lowell.