2015 by the Board of Regents of the University of Wisconsin System. We study an intensive math instruction policy that assigned low- skilled ninth graders to an algebra course that doubled instructional time, altered peer composition and emphasized problem solving skills. A regression discontinuity design shows substantial positive impacts of double- dose algebra on credits earned, test scores, high school graduation, and college enrollment rates. Test score effects underpredict attainment effects, highlighting the importance of long- run evaluation of such a policy. Perhaps because the intervention focused on verbal exposition of mathematical concepts, the impact was largest for students with below- average reading skills, emphasizing the need to target interventions toward appropriately skilled students.