The theme of this session is the composition, structure, dynamics and evolution of the mantle. We invite participation from a spectrum of disciplines, from seismic tomography, mineral physics, experimental petrology, geochemistry and numerical modeling to understand how the mantle functions and how it evolved to its current state. Some specific processes to be considered include the origin and evolution of large low shear velocity provinces (LLSVP), the interaction between plate tectonics and other modes of convection, the fate of subducted slabs, melting and the segregation of magma, recycling from the surface into the sources of mantle plumes, and the deep mantle volatile cycle.