Particulate matter (PM) emitted from bio-fueled cook-stoves is a large contributor to lower respiratory illness in developing nations. In addition, particulate matter significantly contributes to global warming and the trees that are harvested for cooking fuels is one of the leading causes of deforestation. Current natural draft cookstoves emissions on average must be reduced by nearly an order of magnitude and efficiency doubled to achieve Tier 4 standards. We are funded by the Department of Energy to develop a Tier 4 wood-fed natural draft stove that meets the needs and desires of East Africans. We are delivering a manufacturable and market ready cookstove the meets the cost and usability expectations of final users, including durability, emissions, safety, comfort, aspirational value and compatibility with local fuels, food, and customs.