As Critical Zone science takes root in the array of disciplines comprised in Earth science and initial observatory results become available, a special section of the Vadose Zone Journal has been published to highlight current and future research efforts. In this edition, contributions to hydrology, biogeochemistry and the interplay between both hydrology and biogeochemistry are reviewed. A total of 14 manuscripts were selected to illustrate advances in the study of the near-surface terrestrial environment. The Table of Contents is available here: Vadose Zone Journal.