Folk belief theory is suggested as a primary cause for the persistence of the achievement gap. In this research-supported theory, culturally specified folk beliefs about learning and teaching prompt educators to direct more rigorous curriculum to high-advantage students but not to low-advantage students, resulting in impoverished pedagogy in disadvantaged schools. Folk beliefs tend to be resistant to change, which helps to explain why the achievement gap has proven so persistent. At the same time, various belief-change strategies have potential to promote use of rigorous curriculum with disadvantaged students.