This work investigates the micro-mechanics of a multiphase steel sheet during a uniaxial tensile test. Based on crystal plasticity theory, one assesses how the distribution of strain and stress is influenced by the presence of a soft b.c.c. phase and a strong f.c.c. phase. The two phases have been characterized by neutron diffraction. Initial textures are used as input in crystal plasticity simulations. Lattice strains measured in the tensile direction serve to fit hardening parameters. Three modeling hypotheses are tested: the Taylor model assumes uniform strain, the ALAMEL model considers the interaction of pairs of adjacent grains, and a finite element mesh is used to distribute strain and stress over the complete aggregate. The accuracy of each modeling is evaluated based on experimental measurements of the macroscopic stress, the heterogeneity of plastic strain, and the texture development in the two phases.