Indoor air pollution causes significant health problems for the 2 billion people worldwide who rely on biomass fuels for their cooking and heating needs. Over the last 30 years awareness of the environmental and social costs of using traditional fuels and stoves has grown. At the same time, studies of the problem have resulted in proven strategies to reduce both fuel use and harmful emissions. Unfortunately, the local stoves currently available do not always represent the best designs that modern engineering can offer. This booklet is an attempt to address the problem by summarizing some of the advances in stove theory and design. Understanding these concepts would be useful to administrators of stove projects, policy makers, field workers, and cooks alike.