The Critical Zone (CZ), encompassing the Earth's outer layer from the top of the vegetation canopy to the bottom of the circulating groundwater, is essential for sustaining life and maintaining environmental health. Understanding this complex zone requires a collaborative, multidisciplinary approach that transcends disciplinary and national boundaries, bridging gaps between short-term and long-term environmental processes. This session will highlight CZ science, CZ methodologies, and the collaborative efforts of CZ networks from around the world. Topics of interest include, but are not limited to: Innovative techniques in CZ research and monitoring, including contributions involving observations, modeling, or integration of the two; Advances in understanding soils, hydrology, and biogeochemical cycling within the CZ; Characterization of CZ structure as it varies with depth and environmental factors; Impacts of stressors and environmental change on the CZ; Policy or management implications of CZ research; Development of CZ science networks; and Case studies of successful international CZ collaborations.