The Council of the Great City Schools supports member districts in creating opportunities for all students to access powerful mathematics that increases mathematics achievement for all students. The Council has long advocated for rigorous expectations for all students in kindergarten through grade twelve. For mathematics, we are developing effective tools, resources, and providing professional development to support school districts in elevating the level of student performance. We collaborate with other professional organizations and school district leaders to support implementation of a high-quality mathematics curriculum, designing and implementing a strong mathematics program that provides access to all, building a shared understanding about opportunity to learn so all students engage, learn, and experience the joy and wonder of mathematics. In mathematics, we also advocate for and support improvements with district-created assessments to effectively monitor student learning and generate better mathematics outcomes. This collaboration supports improving practice and student learning in mathematics for the largest urban districts across the nation so that our children are college and career ready when they graduate from high school.