A study of the detailed mechanical response of a galvannealed dual phase steel has been undertaken together with a detailed analysis of the role of various microstructure components. In the fracture behavior, it was established that at temperatures above -65°C, damage occurred by void nucleation and growth at the ferrite-martensite interface leading to ductile fracture. At -196°C, the dominant damage process was by cleavage initiated in the embedded martensitic phase. Fractographic studies revealed that both size and the distribution of the martensitic phase, which is related to banding of the Mn, plays an important role in the fracture process both in tension and in bending.