The conventional view is that the origin of the black-white student achievement gap can be traced to sociocultural and socioeconomic factors, plus variation in parental style and parental investment, and is maintained and perpetuated by variation in school and teacher quality. This article rejects the conventional view, drawing upon the results of a league-table evaluation of the cost-efficiency of 23 interventions to raise student achievement. While sociocultural and socioeconomic factors plus variation in parental style and parental investment contribute to initial disparities in performance, the results support the hypothesis that these disparities are maintained, perpetuated, and exacerbated by demoralizing grading, testing, and grouping practices throughout the K-12 years. The pattern of results is not consistent with any other explanation for the achievement gap.