Non-rainfall water inputs (NRWIs), i.e., a gain of water to the surface soil layer that is not caused by rainfall, comprise fog deposition, dew formation, and water vapor adsorption. In drylands, the annual amount of NRWIs sometimes exceeds that of rainfall and, in many areas, NRWIs are the sole source of liquid water during the long dry summer. NRWIs in drylands are known to significantly contribute to the water cycle. It has been suggested that they also contribute to biogeochemical dynamics through promoting microbial activity and nutrient recycling in the upper few centimeters of the soil profile. Their ecological and environmental role in dryland ecosystems is thus important, but far from being fully understood. We invite contributions on the quantification of NRWIs by measurements and modeling, and on their effect on ecosystems, both natural and agricultural.