Combinations of failure mechanisms are frequently encountered in the life prediction of composite materials. Life prediction methodology presented by Reifsnider et al is applied to one such failure mechanism combination. This method uses experimental data and analytical tools to predict the long-term behavior of a composite under service conditions. This prediction scheme is based on the assumption that damage accumulation progressively reduces the remaining strength of a composite. An overview of the fundamental concepts of the life prediction method is presented. The method is used to model the elevated temperature fatigue behavior of a unidirectional AS-4 carbon fiber / PolyPhenylene Sulfide (PPS) matrix composite material. The nonlinear combined effects of time at elevated temperature and fatigue are taken into account by considering elevated temperature tensile rupture and room temperature fatigue behavior. The life prediction for the combined loading is compared to 90°C tensile-tensile fatigue data. This comparison shows good correlation between the prediction and data and demonstrates the method’s effectiveness in life prediction modeling.