This study examines the impact on student achievement of implementing a bundle of best practices from high-performing charter schools into low-performing, traditional public schools in Houston, Texas, using a school-level randomized field experiment and quasi-experimental comparisons. The five practices in the bundle are increased instructional time, more effective teachers and administrators, high-dosage tutoring, data-driven instruction, and a culture of high expectations. The findings show that injecting best practices from charter schools into traditional Houston public schools significantly increases student math achievement in treated elementary and secondary schools-by 0.15 to 0.18 standard deviations a year-and has little effect on reading achievement. Similar bundles of practices are found to significantly raise math achievement in analyses for public schools in a field experiment in Denver and program in Chicago.