The influence of stress path on the stress-strain behavior of a Florida sand subject to repetitive moving wheel loads is investigated in the laboratory with conventional triaxial equipment. A conventional resilient modulus test with only cyclic varying compressive loads and a moving wheel stress path involving both extension and compressive loads determined from an elastic solution were examined at different initial confining pressures. The tests showed that excursions of applied extension loading followed by compression loading resulted in anisotropic material behavior. This, in turn, influenced both the cyclic permanent strain (rutting) build-up as well as the resilient (distortion) behavior of the material for initial confining pressures below approximately 40 psi (276 kPa). It was concluded that, in order to model both the distortion and rutting characteristics of a sand, improved constitutive relationships over the simple linear elastic theory are warranted. A bounding surface plasticity model was subsequently developed based upon both the plastic shear dilation and volumetric behavior of the sand. The predicted model response agreed both qualitatively and quantitatively for the tests investigated.