We give a theoretical development of a uniformly valid solution for describing the polar motions of a layered viscoelastic earth. Such solutions require the usage of two classes of eigenspectra to describe the processes of rotational deformationn an viscous relaxation. One set consisting of real eigenvalue describes the isostatic relaxation of the mantle by viscous creep. The second one governs the readjustment of the rotational axis of the viscoelastic earth, and the eigenspectrum is complex valued. These solutions are capable of describing rotational phenomena ranging from CChandler wobble excitation to long-term polar drift. A comparative study is conducted between the complete solution for polar wander and one in which a number of the rotational modes has been truncated. For a four-layer model consisting of an elastic lithosphere, a two-layer, adiabatically stratified viscoelastic mantle, and an inviscid ore, such a comparison shows that at most a 30% difference exists in the viscosity solutions of the lower mantle, which are obtained by fitting the theoretical predictions to the observed polar wander data. Although the polar speeds from the various models can vary by as much as a factor of 2, the differences in the inverted visosity solutions are sharply reduced upon fitting the calculations with the actual data for the time window, between 5 and 7¿103 years, which characterizes the hiatus between the termination time of the deglaciation period and today. The averaged polar drift from typical glacial cycles in the Pleistocene shows an initial magnitude of 0(1¿/m.y.), which after a few million years decays to a steady state value of a few tenths of a degree per million years.