This presentation reports the application to vegetation canopies of a coherent model for the propagation of electromagnetic radiation through a stratified medium. The resulting multi-layer vegetation model is plausibly realistic in that it recognizes the dielectric permittivity of the vegetation matter, the mixing of the dielectric permittivities for vegetation and air within the canopy, and, in simplified terms, the overall vertical distribution of dielectric permittivity and temperature through the canopy. The model parameters required to specify the dielectric profile within the canopy, particularly the parameters that quantify the dielectric mixing between vegetation and air in the vegetation canopy, are not usually available in typical field experiments. Thus, the feasibility of specifying these parameters using an advanced single-criterion, multiple-parameter optimization technique was investigated. The results imply the mixing parameters can be so determined, but only if other parameters that specify vegetation dry matter and water content are measured independently. This model was then applied to investigate how the presence and nature of vegetation cover influences the soil moisture, effective temperature, and vegetation water content retrieved using multi-angle passive microwave observations, with the SMOS mission as a case study.