Solar lanterns are promoted across rural Sub-Saharan Africa as a way to improve educational outcomes. A randomized controlled trial in Zimba District, Zambia, evaluates whether solar lanterns help children study and improve academic performance. The research design accounts for potential income effects from receiving a lantern and also "blinds" participants to the study's purpose. There is no relationship detected between receipt of a solar lantern and improved performance on key examinations. Impacts on self-reported study habits are also not observed. A cost-effectiveness analysis suggests that solar lanterns are not an efficient way to improve educational outcomes in developing countries relative to other available options. Two phenomena, both of which are likely observed in other developing regions, may explain these results. First, flashlights have become the dominant lighting source in rural Zambia, so solar lanterns may have only limited appeal for prospective users who no longer rely on traditional lighting options like kerosene lamps. Second, improved energy access - whether through solar lanterns or other technologies - appears to be a relatively unimportant educational input in settings like Zimba.