At the phase level of the microstructure, a model based on micro mechanical modeling of cells is developed to capture the mechanical behavior of the dual phase (DP) steel consisting of Martensite in a matrix of Ferrite. DP-steels having different volume fractions of Martensite are produced from heat treatment of low carbon steel. Results of tensile tests are compared to the micro mechanical model in which only the single phase Ferrite and Martensite phase behaviors are used as input. The results show good agreement between the experiment and model in terms of stress strain curves and in terms of mechanics of deformation.