Wildfires and prescribed burns are common throughout Arizona and California chaparral. Predicting fire effects requires understanding fire behavior, estimating soil heating, and predicting changes in soil properties. Substantial quantities of some nutrients, particularly nitrogen and phosphorus, are lost directly during combustion. Highly available nutrients released during a fire are deposited on the soil surface where they are immobilized or lost by erosion. Information on the effect of fire on physical, chemical, and biological soil properties provides a basis for discussing short- and long-term consequences of postfire rehabilitation treatments on total nutrient losses, changes in nutrient availability, decreased infiltration rates, and erosion. Arizona and California chaparral show both similarities and differences.