Whether or not more effective schools can successfully mitigate the impacts of early disadvantage upon educational attainment remains uncertain. We investigated 2,664 children aged 6-11 years and measured their academic skills in English and maths along with self-regulation at 6, 7, and 11. Experiencing multiple disadvantages before age 5 strongly impaired later self-regulation and academic attainment. However, attending a more academically effective primary school for just a single year was found to partially protect all outcomes at age 6. In addition, more academically effective primary schools significantly lessened the extent to which earlier abilities in reading, writing, and self-regulation predicted these same abilities at age 11. Thus, although attending a more academically effective primary school does not eliminate the adverse impacts of multiple disadvantage experienced at a younger age, it can mitigate them by promoting better academic attainment and self-regulation up to age 11 for children who had experienced more disadvantages. (Contains 4 tables and 2 figures.)