In the face of stagnant achievement and persistent achievement gaps in mathematics, school districts have enacted a variety of changes to varying levels of success. On the heels of an Algebra for All model that failed to generate desired outcomes of students, San Francisco Unified School District adopted a policy in 2014 that dramatically changed its sequence of mathematics courses. The district completely de-tracked its middle school classes, enrolling all students in the same heterogeneously grouped courses for Grades 6, 7, and 8. San Francisco's policy represents a significant departure from traditional approaches to organizing mathematics courses, and early outcomes appear to validate this approach. This brief describes the rationale behind the district's decision, the nature of the new policy, and the promising results the district has experienced so far.