Passive microwave measurements of the Bering Sea ice cover were made with the NASA CV-990 airborne laboratory and with the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) during February 1983 as part of the Bering Sea marginal zone experiment (MIZEX West). Microwave data obtained with the CV-990 include radiances from both imaging and dual-polarized fixed-beam radiometers spanning a range of frequencies from 10 to 183 GHz. The imagery at 19 and 92 GHz provide a description of the marginal ice zone delineating regions of open water, ice compactness, and ice-edge structure. Comparison of these images with ice concentration maps derived from the SMMR data shows that the maps provide an accurate description of the ice edge and interior pack polynyas. Analysis of the fixed-beam data shows that spectral differences increase with a decrease in ice thickness and the polarization at both 18 and 37 GHz distinguishes among new, young, and first-year sea ice types. Finally, these results are shown to agree with surface-based radiometric measurements.