Household investment in preventative health products is low in developing countries even though benefits from these products are very high. What interventions most effectively stimulate demand? In this paper, we experimentally estimate demand curves for health products in Kenya, Guatemala, India, and Uganda and test whether (1) information about health risk, (2) cash liquidity, (3) peer effects, and (4) intra-household differences in preferences affect demand. We find households to be highly sensitive to price and that both liquidity and targeting women increase demand. We find no effect of providing information, although genuine learning occurred, and we find no evidence of peer effects, although subjects discussed the product purchase decision extensively. (C) 2013 Elsevier B.V. All rights reserved.