Watershed managers and scientists throughout the world have been aware of fire-induced water-repellent soils for over three decades. Water repellency affects many hydrologic processes, including infiltration, overland flow, and surface erosion (rill and sheet erosion). This paper describes; the formation of fire-induced water-repellent soils, the effect of soil water repellency on infiltration and runoff, erosional processes unique to water-repellent soils, and the results of watershed and plot studies used to evaluate watershed-level responses to water repellency.