This paper reports results from a field experiment in Uganda. The proportion of children five years and younger who slept under a mosquito net was 20 percent higher when nets were distributed for free compared to when an equivalent cash transfer could be used to purchase nets. This effect is attributable to the endowment effect (more nets were retained when received for free than offered for sale), and to differences in how purchased and free nets are allocated within the household. Nets received for free were more likely to be used by young children. Purchased nets, on the other hand, were used by those members of the household, often adults, perceived by participants to suffer from malaria most frequently. When a married woman acquired nets, the probability that her children used these increased with the educational attainment of her husband.