Traditionally, the kinematic hardening assumption is used in conjunction with an assumption that the stress-strain curve for simple tension can be approximated by a bilinear curve. This paper generalizes the concept of kinematic hardening for the case when the stress-strain law is nonlinear. It is shown that although a yield condition of the form with κ constant or variable cannot represent non-linear kinematic hardening, at least one yield condition of the form where , represents such hardening.