In this work, the evolution of internal lattice strains in face-centered cubic stainless steel under uniaxial tension is studied using a recently developed full-field elasto-viscoplastic formulation based on fast Fourier transforms. The shape of the diffraction peaks is simulated, and the predicted lattice strains (peak shift and broadening) are compared with the experimental measurements obtained by in situ tensile neutron diffraction. Detailed analysis of the lattice strain distributions reveal that 1 0 0 and 1 1 0 transverse families exhibit a bimodal nature, and that transverse lattice strains are more sensitive to local grain interactions compared with longitudinal lattice strains. A comparison with the results of a mean-field formulation indicates that type III (intragranular) stresses play a much larger role than type II (intergranular) stresses in diffraction peak broadening. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.