Neutron and X-ray diffraction techniques have been utilized to map residual stresses in MIG welded 7150 aluminium alloy plates with a high texture. Longitudinal (parallel to the weld seam) strain measurements were made using 40 keV X-rays whilst normal (through-thickness) and transverse strains were measured using neutrons at a pulsed spallation source. The strains have been corrected for the strong chemical composition variation across the weld. The complementarity of the methods was confirmed by comparing the strain obtained in the transverse direction. The combined results of both diffraction experiments enabled the full 3D stress tensor to be mapped across the weld in an optimized manner.