Significance This randomized, controlled trial demonstrates that by relieving a constraint on household nutritional assets, here through reducing chicken mortality through vaccination, households make dietary choices for young children that increase consumption of protein- and micronutrient-rich foods and decrease relative consumption of high-carbohydrate, low-protein grains. The study provides causal evidence that this shift in diet results in improved height for age, a key measure of childhood stunting. Given the high prevalence of childhood growth failure in rural Africa, these results highlight the potential to increase the utility of a common household animal asset to reduce the burden of childhood stunting in these communities.