This volume examines the current state of knowledge concerning the influence of a hot environment on nutrient requirements of military personnel. A parallel concern is ensuring that performance does not decline as a result of inadequate nutrition. The committee provides a thorough review of the literature in this area and interprets the diverse data in terms of military applications. In addition to a focus on specific nutrient needs in hot climates, the committee considers factors that might change food intake patterns and therefore overall calories. Although concern for adequate nutrition for U.S. soldiers in Saudi Arabia prompted the initiation of this project, its scope includes the nutrient needs of individuals who may be actively working in both hot-dry and hot-moist climates.