Pré-publication, Document de travail: This paper analyzes the effect of malaria prevalence and indoor residual spraying on the probability of sleeping under an insecticide-treated bed net in nine Sub-Saharan countries. Specifically, it examines whether bed net usage is elastic with respect to malaria prevalence and whether indoor residual spraying, which is a public intervention, crowds out bed net usage, which is a private behavior. Using data on individual bed net usage and household indoor residual spraying combined with local malaria prevalence, we show that malaria prevalence has a positive effect on bed net usage, but that bed net usage is inelastic with respect to malaria prevalence, with elasticity ranging from 0.42 for adult women to 0.59 for older children, in our preferred model. We also find that indoor residual spraying does not crowd out bed net usage. Instead, individuals who live in houses that were recently sprayed are more likely to use a bed net.