This chapter describes how arid hillslopes are affected by the primary sources of energy in deserts: wind, salt, water, life, and seismicity. Though quantification of these processes is incomplete, these landscapes still contribute to our understanding of hillslope response to climate change (and desertification) and inform our interpretation of extraterrestrial, rocky hillslopes. Keywords: Abiotic, Arid, Atacama Desert, Bioturbation, Cosmogenic radionuclides, Desert, Erosion, Hillslope, Hyperarid, Namib Desert, Negev Desert, Overland flow, Salt, Vegetation.