Cool roof technologies, especially cool roof paint, offer a low-cost, easily scalable, and low-emission alternative to energy-intensive air-conditioning for reducing heat exposure in buildings – an increasingly urgent need in developing countries facing rising temperatures due to climate change. We evaluate the effectiveness of a cool roof intervention – white reflective paint applied to the roofs of government pre-schools (Anganwadis) in Thiruvananthapuram district of the Indian state of Kerala—using a randomized controlled trial. The cool roof paint reduces indoor temperatures in treated pre-schools by approximately 1.3◦C. Staff in treatment pre-schools report significantly lower thermal discomfort. We also find meaningful improvements in children’s cognitive performance, amounting to roughly 6.4% of the baseline mean. The intervention has no detectable effect on children’s attendance. Overall, our findings demonstrate that cool roofs can serve as a practical and scalable adaptation strategy to mitigate heat stress in low-resource educational settings.