Abstract A method of analysis of both the elastic and plastic strains in a face-centred cubic crystal under a given path of strain is shown. The consideration of elastic strain shows the effect of the curve of critical shear stress vs. the sum of slips in the crystal, on the activation of the five active slip systems under a uniaxial strain. This method gives the sequence of active slip systems in the process of loading. This enables the calculation of the transition from one set of active slip systems to another for a crystal deformed under varying ratios of principal strains. The slip systems on active planes, on which sliding is taking place, are taken to harden little less than those on the other crystal planes. This differential hardening and the sequence of active slip systems serve to reduce the number of possible combinations of five active slip systems, so the rotation and the orientation of a crystal under deformation can be more closely determined.