Polarimetric SAR interferometry (PolInSAR) is a recently developed synthetic aperture radar (SAR) imaging mode that combines the capabilities of radar polarimetry and interferometry, as well as adding new capability from a synthesis of the two techniques. PolInSAR holds the promise of being able to provide unique data that can be of great value to the earth science community. By observing scattering volumes such as vegetation canopies, ice sheets, and dry soils using this new SAR technique, one can obtain and decompose scattering from within that volume. In traditional SAR imaging, all scattering that arises from within a three-dimensional resolution cell of the volume is collapsed into a single pixel value due to the layover effect. PolInSAR provides a method of separating the various scattering center locations based on their polarimetric properties. PolInSAR techniques, therefore, can address many issues of interest to the vegetation and environmental community, providing measurements of foliage structure and density, and potentially contribute directly to our understanding of the carbon cycle budget.