The Critical Zone (CZ) is a dynamic region where rock, soil, water, air, and living biota interact to shape Earth’s surface. The Critical Zone ranges from the tops of the trees to the bottom of groundwater. The field of hydrogeophysics employs geophysical methods to determine parameters and monitor processes associated with water resources, the water cycle, and contaminant transport to inform hydrogeological studies. All of CZ science could benefit from the temporal and spatial information provided by hydrogeophysics; however, to date the two fields have evolved largely in parallel. In this workshop, we propose to develop a framework for advancing both hydrogeophysics and CZ science through communicating and coordinating research agendas. New insights into CZ processes will be gained through the enhanced use of hydrogeophysics, and the detailed interdisciplinary observations made in CZ studies will provide opportunities for advancing hydrogeophysical methods.