The present document was conceived to address the needs of a growing body of individuals working with soil fate and transport models. A variety of stochastic and deterministic soil leaching models have been developed in the past decade, particularly to measure the transport and transformation of organic pollutants moving through the vadose zone. The U.S. Environmental Protection Agency (USEPA) has supported the development and testing of three such models, largely for screening purposes: The Seasonal Soil Compartment Model (SESOIL), the Pesticide Root Zone Model (PRZM), and the Pesticide Analytical Model (PESTAN). The document seeks to provide the reader with a general overview of the uses and limitations of vadose zone models.