Household investment in preventative health products in developing countries is typically low even though the returns to such products are high. In this paper, we experimentally estimate demand curves for health products and test whether (1) information about health risk, (2) cash liquidity, (3) peer effects, and (4) intra-household differences in preferences affect demand. In our main experiment in Kenya involving children’s shoes - critical for preventing hookworm infection - price is by far the most important predictor of purchase. Providing liquidity and targeting women also increased demand. Information had no effect even though we find that genuine learning occurred. We find no peer effects even though people discussed the product purchase decision extensively. We find similar results for price and information in three smaller studies in Guatemala, India, and Uganda in experiments involving soap and multivitamins.