Two surface-based, portable, S-band and C-band polarimetric scatterometers intended for in situ measurements of both terrain and the ocean’s surface are presented. The scatterometers' layout, hardware design, measurement accuracy, calibration, and signal processing concepts are described. To augment in situ geophysical observations, researchers have often employed in situ scatterometers for validating satellite-based retrievals and also for their innate ability to monitor geophysical variations of localized regions with fine temporal resolution. Backscatter measurement variability due to system effects is presented, providing the fundamental basis for the quantitative analysis of data. Sample polarimetric retrievals are presented for asphalt pavement and grass.