Much of the population in developing countries uses firewood for cooking. The resulting indoor air pollution has severe health consequences for children who are close to the fire while their mothers cook. We use survey data from Guatemala to examine the effects of firewood consumption on the health of children up to five years of age. We also investigate the impact of cooking inside the home, the importance of a mother cooking while caring for her children and the role played by the smoke permeability of housing construction materials. We find that children living in households that use more wood, and where exposure to indoor air pollution is higher because the mother cooks while caring for children or because cooking takes place inside, are more likely to have symptoms of respiratory infection. Simulations indicate that policies that target cooking habits in order to directly reduce exposure, particularly by reducing the number of women who simultaneously cook and care for children, may be more effective for improving young children's health than policies to accelerate the adoption of gas stoves.