A model has been developed for the prediction of yield stress of cast alloys. It consists of integrated unit step models of the physical metallurgy of solidification, solid-state transformations, structural hardening and micro-mechanisms. Calibration of the precipitation and hardening unit step models is conducted based on experimental data available in the literature for aluminium–copper alloys. Applications are then carried out to study the effects of material and process parameters such as grain size, alloy composition, solidification cooling rate, duration and temperature of the homogenisation and precipitation heat treatments, as well as quenching rate after homogenisation. The effect of the residual volume fraction of eutectic after completion of the solidification and homogenisation treatments is clearly revealed as the main parameter controlling a yield stress knock-down factor.