Sustainable milk production in developing countries must address food security and climate change mitigation simultaneously. Socioeconomic sustainability is paramount in developing countries where milk production and consumption represent a vehicle to improve human nutrition and health, as well as the potential for increased income, leading to improved livelihoods by subsistence farmers with limited access to markets. These benefits can only be achieved with judicious use of animal stocks and agricultural practices that do not exhaust available natural resources, which are often shared by regional farming communities. Milk and dairy foods provide balance and variety to the diet and make significant contributions to meeting the needs for calcium, magnesium, selenium, riboflavin, vitamin B₁₂ and pantothenic acid (vitamin B₅) in undernourished populations and especially children. Milk production in developing countries largely occurs in smallholder mixed crop-livestock systems where the animals may suffer from malnutrition leading to negligible or no milk production during several months of the year. Livestock are also valued for non-food functions such as draft, fuel (manure), store of capital and insurance against crop failure incentivizing the maintenance of large unproductive herds that place stress on feed (land) and water resources. Under these circumstances, sustainable intensification–increasing milk production from currently available resources–represents the single most important and practical strategy for improving the sustainability of milk production and consumption in developing countries. Improving the genetic potential of the animals, the availability of quality feed, and providing balanced nutrition are the most promising strategies to improve milk production and sustainability in developing countries. For example, the productivity gap for milk in Ethiopia is estimated at 4.5 billion L/year, which can be closed, in part, with balanced nutrition. Milk production in developing countries will be sustainable if it supplies more essential nutrients to under and malnourished populations while utilizing the natural resources available.