The influence of void nucleation occurring during the deformation history on shear localization is investigated by employing a constitutive model of a rate independent porous plastic solid. Both plastic strain controlled and stress controlled nucleation processes are simulated. Two deformation histories are considered, one corresponding to uniaxial tension and the other to plane strain tension. The enhanced triaxiality at the center of a neck is simulated by application of Bridgman's solution for the stress and deformation state at the minimum section of a necked bar. The destabilizing effect that arises when void nucleation is stress controlled and nucleation occurs over a narrow range of stress is illustrated. Results are also presented employing parameter values representative of spheroidized carbon steels employed in a recent experimental study carried out by Fisher [23] and the predictions of the model are discussed in light of the experimental observations.