Physical aging at elevated temperatures of the advanced composite IM7/K3B was investigated through the use of creep compliance tests. Testing consisted of short-term isothermal, creep/recovery with the creep segments performed at constant load. The matrix-dominated transverse tensile and in-plane shear behavior were measured at temperatures ranging from 200 to 230°C. Through the use of time-based shifting procedures, the aging shift factors, shift rates, and momentary master curve parameters were found at each temperature. These material parameters were used as input to a predictive methodology that was based upon effective time theory and linear viscoelasticity combined with classical lamination theory. Long-term creep compliance test data was compared to predictions to verify the method. The model was then used to predict the long-term creep behavior for several general laminates.