This chapter formulates systematically the Earth tide and surface loading of the spherical elastic Earth model. The Earth tide is the deformation of the Earth in response to the variable gravitational attraction of extraterrestrial celestial bodies. The surface loading is the deformation of the Earth in response to the variable gravitational attraction and surface pressure of the mass transport in the atmosphere-hydrosphere-cryosphere system. The subjects concerned include tidal-generating force and potential, development of the tidal-generating potential into harmonic waves, the tidal Love numbers, the observables affected by Earth tide, the dynamic and static load Love numbers, the asymptotic expressions of the load Love numbers, the load Green’s function, and the practical computation of loading effects. Some closely related geophysical problems including the definition of the geocenter, the gravitational potential of ocean tide and its loading effect, and the pattern of sea level change as a result of present-day continent-ocean water exchange, are also formulated.