The vadose zone is the region between ground level and the upper limits of soil fully saturated with water. Hydrology in the zone is complex: nonlinear physical, chemical, and biological interactions all affect the transfer of heat, mass, and momentum between the atmosphere and the water table. This book takes an interdiscipliary approach to vadose zone hydrology, bringing together insights from soil science, hydrology, biology, chemistry, physics, and instrumentation design. The chapters present state-of-the- art research, focusing on new frontiers in theory, experiment, and management of soils. The collection addresses the full range of processes, from the pore- scale to field and landscape scales.