The monograph is concerned with a generalization of the results of regional geodynamic research in Siberia. First and foremost, analysis of the Earth's crust structure for Siberian platforms and certain regions of mountain framing enables us to reveal some geodynamic features of the upper mantle structure. The lithosphere of Siberia contains no active sources of the geodynamic processes determining the formation and evolution of its regional structures. The basic processes of modern geodynamics in respect to Siberia's lithosphere are represented by external forces that may be of various nature: The interaction of lithospheric plates (in their lateral shifting) results in a compression of the Siberian Platform at the sides adjacent to the Verkhoyan-Kolym and Central-Asian mountain ridges, in straining of these ridges and forming of local tension areas within the Baikal rift. The evolution of the lower-mantle channel of mass and heat transfer in the Baikal region causes a series of mechanical, thermal and petrological variations in the lithospheric structure of the region and specifies certain tectonic and magmatic processes. The principal mantle process initiating tectonomagmatic development of the Siberian lithosphere is represented by transient lower-mantle mass and heat transfer. Its channel has been discovered by teleseismic monitoring of the Baikal region. The process of recent tectonic activation of the lithosphere of South Siberia is now at the stage of channel cooling under inhomogeneous stressed state of the lithosphere due to interaction of plates in their lateral shifting. Rheological mantle stratification (which is most prominent in the transitional zone and still remains significant above it) is responsible for the predominance of subhorizontal mantle currents and differential plate displacements in activated lithospheric regions. These displacements tend to level the structural inhomogeneities owing to tectonomagnetic manifestations of mantle diapirism. Thick cold lithosphere of the Siberian platforms does not preclude lateral flows in the upper mantle (with flow rates less than 10 cm per year).