Traditional monitoring methods using chemical analysis of groundwater samples to detect pollutant migration are being superseded or used in conjunction with innovate approaches. A need to detect pollutants before they reach the water table has drawn interest to vadose (unsaturated) zonemonitoring and brought together hydrogeologists, soil scientists and agricultural engineers who have been working on this subject for years. Recent studies have identified over 50 different types of vadose zone monitoring devices and methods that have optimum utility in varying hydrogeologic settings. In general, measurements made in the vadose zone are trying to define storage, transmission of liquid waste in terms of flux and velocity, and pollutant mobility. Criteria for the selection of alternative vadose zone monitoring methods are important for the development of site-specific systems. These criteria include: type of site; applicability to new, active, and abandoned sites; power requirements; depth limitations; multiple use capability; type of data collection system; reliability and life expectancy.