High temperatures have been shown to have impacts upon health, labor productivity, and many other aspects of aspects of well-being. While air-conditioning is highly effective at reducing many of these impacts, a substantial population globally do not have the resources to adapt to high temperatures in this way. Adaptation to high temperatures in the face of climate change for developing countries thus presents a substantial challenge. Passive cooling, via reflective paints on roofs, provides an opportunity to extend these adaptation benefits to low-income settings. These “cool roofs” have been much discussed by policy makers in India, in particular. Between 2017 and 2018, we conducted the largest experimental evaluation of cool roofs to date, enrolling 500 households in a low-income community outside of Delhi. Preliminary results demonstrate modest effects on indoor temperatures and household expenditures on cooling.