Despite growing concerns from regulators about potential price discrimination against sustainable investors, empirical evidence is lacking. To address this gap, we conduct two lab-in-the-field experiments with 415 professional financial advisors from the US and Europe. Our results show that these advisors impose a premium on sustainable investors compared to conventional investors. This premium persists even when differences in effort, skill, and costs, as well as higher gains from trade are ruled out. Notably, advisors charge the highest fees to sustainable investors with low financial literacy, while sustainable investors with high financial literacy pay no premium at all. These results are consistent with price discrimination. Financial regulators evaluate our results and provide policy implications.