The motion of tectonic plates is not fully compatible with a purely mantle-driven system where plates only passively drift. Because of their thermal and mechanical properties, plates exert a feedback onto mantle dynamics that evolves through time. The tectonic record can monitor the spatial and temporal variations of forces driving and resisting plate motions. Stress and strain indicators, as well as mountain building, erosion and sedimentation, and other geological and geophysical observables can be viewed as indicators of the evolving force balance and interactions between plates and mantle. The scope of this session is to bring together observations and interpretations that help quantify the history and balance of forces between mantle and plates. We encourage contributions from field-based as well as modeling (both analog and numerical) studies on the dynamics of the lithosphere and its ability to feed back on mantle convection.