Dual phase steels are prime candidates for automotive lighweighting due to their high yield and tensile strengths and high initial work hardening rate. These properties have been shown to be dependant on the volume fraction and scale of the non-ferritic reinforcement phase. In the present study, rapid intercritical heat treatments were used to change the scale and microstructure of the non-ferritic phase in cold rolled, spheroidised and quenched and tempered DP600 microstructures with the intercritical annealing temperature being approached from below (i.e. starting at room temperature) and above (i.e. from the austenitising temperature). In the former case, the scale and distribution of the non-ferritic phase was significantly changed for all of the starting materials and, in the case of the cold rolled and quenched and tempered starting microstructures, the yield stress, tensile strength and yield/tensile ratio were significantly increased versus the industrially processed materials without a significant decrease in uniform elongation. Thus, it was shown that rapid heat treatments can be used successfully to improve the microstructure and mechanical properties of dual phase steels.