Age hardening of aluminum alloys is done to improve the alloy strength and other mechanical properties of interest.  To optimize the properties, the aging schedule, i.e. aging time and temperature, is often chosen empirically.  A more efficient way for optimizing the properties would be a model capable of predicting the microstructure and the properties as a function of aging schedule and the alloy compositions.  A wide variety of mechanisms has been reported in the literature describing the interaction between precipitates and the motion of dislocation during aging.  In this study a micromechanical model for precipitation strengthening during aging of aluminum alloys has been developed based on the equations governing these mechanisms to predict the yield strength as a function of aging schedule.  The model incorporates the salient microstructural features, such as precipitate size, shape and distribution, to explain the strengthening during aging process.