This paper investigates the impact of schools banning mobile phones on student test scores. By surveying schools in four English cities regarding their mobile phone policies and combining it with administrative data, we find that student performance in high stakes exams significantly increases post ban. We use a difference in differences (DID) strategy, exploiting variations in schools’ autonomous decisions to ban these devices, conditioning on a range of student characteristics and prior achievement. Our results indicate that these increases in performance are driven by the lowest-achieving students. This suggests that restricting mobile phone use can be a low-cost policy to reduce educational inequalities.