A new, unified model simulates many of the structurally significant deformation phenomena associated with both creep and short-time plasticity, including cyclic hardening/softening, Bauschinger effect, strain-rate effects, and annealing, among others. It is phenomenological and macroscopic in nature, but is strongly related to the underlying microscopic physical mechanisms. It consists of a single hyperbolic sine strain-rate equation, plus two work-hardening/recovery equations for the rates of change of the two history variables. The derivation, behavior, and use of the model are explained, and the procedure for calculation of materials constants from standard test data is given. Comparisons are made with some other current strain-rate formulations.