The dimensional stability and mechanical and optical properties of injection molded articles are affected to a large extent by the distribution of residual stresses. The distribution of residual stresses varies as a result of the temperature and pressure history during the process. In this paper, two thermoelastic models were used to study the effect of processing conditions on generation of thermal stresses. Then, based these models, two inverse models were developed to calculate the unknown pressure history and initial melt temperature from a known residual stress distribution in the final product. The models were successfully tested with stress data simulated by the forward models. The effect of experimental errors on the inverse methods was investigated by adding measured stress profiles were used to further test inverse models. The results are presented and discussed.