The Council of the Great City Schools supports member districts in raising the mathematics achievement levels of all students. The Common Core State Standards (CCSS) have been informed by the best available evidence and the highest state standards and international benchmarks. Additionally, CCSS has established rigorous expectations for student work at every grade level K-12. For mathematics, we are focused on the development of effective tools, resources, and professional development to support school districts in raising the level of student performance. We collaborate with the writers of the Common Core, with other professional organizations and school district leaders to build a shared understanding of the instructional shifts and their implications for curriculum, assessment, and professional development. This collaboration will support teaching and learning in the largest urban districts across the nation so that our children are college and career ready when they graduate from high school.