LBL-17877The relativistic ponderomotive hamiltonian is derived under as general conditions as possible. Arbitrary kp, E,,/E..L' w/Q, vic < 1, wave polarization, spatial modulation of the wave, and nonuniformities in the background electric and magnetic fields are introduced in a systematic way. This calculation is a modification of guiding center theory, because in addition to averaging over gyration, there is also an averaging over rapid oscillations of the wave. Therefore, as a by-product of our objective, we derive a new formulation of the relativistic guiding center motion •