In this work a Lagrangian approach was used to simulate the crystallinity gradients in injection moulded PPS. This was done through the use of markers whose thermomechanical history was traced as they moved in the cavity. The results of the simulation are compared with our earlier experimental observations. It has been found that there is a good quantitative agreement between the experimental and calculated values of gapwise (ND-TD plane) and lengthwise (FD-ND plane) crystallinity distribution. The calculated results for morphological variables such as the thickness of crystalline layers and their overall span agreed well with the experimentally measured values.