In 1995-2001, investigations were carried out in the Barents and Kara seas on the geotraverses 1-AR (Zapolyarnyi, Kola Peninsula-Heiss Island, Franz Josef Land) and 2-AR (from the center of the 1-AR profile through Novaya Zemlya to the Yamal Peninsula) within the framework of the Federal Program for the Deployment of the State Network of Basic Geophysical Profiles. The total length of the profiles was 2200 km. A complex of geophysical methods, including deep seismic sounding (DSS) and reflection-common depth point (CDP) methods, were used on the 1-AR profile, while DSS observations alone were performed on the 2-AR profile. The profiles were measured with the use of a dense observation system: ocean-bottom stations had an average spacing of 5-20 km, and the interval between excitations (seismic traces) was 250 m. Records of useful waves were obtained at offsets of up to 150-250 km. The crustal thickness of the Barents-Kara shelf plate averages about 35 km. Beneath deep basins filled with low-velocity sediments (the North Barents and Kara basins), the thickness of solid crust is reduced to 10-15 km, with the Moho rising to 28-30 km. The 1-AR profile clearly defines three large blocks differing in the structure of crust: the Kola monocline characterized by marked thickening of the sedimentary cover and thinning of the crust, the central block with thick ancient sediments and a seismically well-expressed basement surface, and the northern block whose wave fields have no signatures of the basement surface. This suggests different tectonic regimes of crustal evolution in these units.