In what has become almost a tradition for Vadose Zone Journal, this special section, Soil Water Sensing, follows two related special sections: Advances in Measurement and Monitoring Methods (Vol. 2, Issue 4, 2003) and Hydrogeophysics, which also focused on measurement methods (Vol. 3, Issue 4, 2004). The tremendous interest in vadose zone monitoring reflects the intense societal interest in understanding our environment, the increasing comprehension of scale-dependence of vadose zone properties and processes, and the rapid changes occurring in sensing methods. In this article, we present an overview of the papers, many of which detail methods that rely on soil electromagnetic (EM) responses, including time domain reflectometry (TDR), ground penetrating radar (GPR), and capacitance methods. The papers also indicate key aspects of sensor performance requiring improvement through further sensor development.