Significant technological advances during the last few years in the field of electromagnetic probing in the meter to submillimeter wave, infrared and optical regions, as well as in data processing and the use of mathematical inverse methods have opened up new avenues in the detection, identification and imaging of natural and man-made objects and gaseous agents in our environment. Information previously considered irretrievable can now be recovered from data disturbed by noise and clutter with the use of more advanced electromagnetic imaging techniques incorporating inverse methods. The incorporation of coherent polarimetric phase information into radar signal and image processing will lead to a breakthrough which is at least comparable to that wrought by the advent of holography and computer assisted tomography and its applications to synthetic aperture radar and inverse synthetic aperture radar. In Direct and Inverse Methods in Radar Polarimetry a major emphasis is placed on the basic principles of electromagnetic wave interrogation with natural and/or man-made media and objects, the optimal structuring of illumination and detection, optimal recovery of useful target signal, mathematical and data processing methods, and representative applications.