The continuous strength method (CSM) is a recently developed deformation-based design method for metallic structures. In this method, cross-section classification is replaced by a normalized deformation capacity, which defines the maximum strain that a cross-section can endure prior to failure. This limiting strain is used in conjunction with an elastic, linear-hardening material stress-strain model to determine cross-section capacity allowing for the influence of strain hardening. To date, the CSM has been developed for the determination of cross-section capacity under normal stresses (i.e. compression, bending and combined loading), where it has been shown to offer more accurate predictions than current codified methods. In this paper, extension of the CSM to the determination of shear resistance is described. The relationship between the normalized shear deformation capacity, referred to as the shear strain ratio, and the web slenderness is first established on the basis of experimental and numerical data. The material model and proposed resistance functions are then described. Comparisons of the developed method with the ultimate shear capacity of a series of tested stainless steel plate girders show that improved resistance predictions of test capacity over current design methods are achieved.