Shelters for protection against the effects of nuclear weapons are often stated to be useless, largely because of firestorms. Recent models purport to show that nuclear weapons are more likely to cause firestorms than previously thought. These controversial models are based on uncertain assumptions, which are difficult or impossible to test. Regardless of the predictive validity of fire models, conclusions about the ability of shelters to protect their occupants against firestorms, if they occur, are based primarily on historical experience. A review of the original data from the Hamburg firestorm shows that almost all persons in adequate shelters survived, contradicting a currently prevailing belief that all died. The results of the strategic bombing during World War II and of nuclear weapons tests show that a considerable level of population protection can be achieved through attention to proper shelter design.