Growth in demand for livestock-derived foods will likely remain strong in low- and middle- income countries, fueling concerns about expansion of production and the management of natural resources. Recent research suggests that the envisioned negative effects are not inevitable and that benefits such as improved food security can be enhanced. Targeted investments to the livestock sector could help make these happen. We use scenario analysis to explore this question, assessing the impacts of selected investment options in sub-Saharan Africa and South Asia. Our results show that boosting livestock productivity primarily in these two regions could improve food security and producer incomes while limiting greenhouse gas emissions and agricultural water usage. Market-improving investments with similar welfare gains lead to environmental impacts that necessitate complementary investments.