The effects of Ti and Zr on the structure and ordering in the (1 −x)Pb(Sc2/3W1/3)O3‐ (x)PbTiO3(PSW‐PT) and (1 −x)Pb(Sc2/3W1/3)O3‐ (x)PbZrO3(PSW‐PZ) systems were studied using synchrotron x‐ray and neutron diffraction. Rietveld refinement was carried out to determine the average long‐range crystallographic structure and pair distribution function (PDF) analysis to probe the local displacements of the atoms. Forx< 0.25 the B‐cations form a 1:1 ordered doubled perovskite structure (space groupFm3¯m). The refined occupancies were consistent with the “random site model”, where the ordered structure consists of one B‐sublattice occupied by Sc and the other by a random mixture of the remaining cations. The B‐site order is reduced by incorporation of Zr, but highly stabilized by Ti with the degree of order in excess of 95&percent; forx⩽ 0.25. The results of PDF analysis show that on the local scale the Pb and O atoms are significantly displaced from their average lattice positions. The PDF curves were simulated by several models of simple Pb and O shifts. The short‐range PDF of PSW could be approximated by allowing Pb shifts along [100] and rotations of BO6octahedra around [101¯]. This model was inadequate for a longer distances (r> 4.25 Å) suggesting the real cation displacements are more complicated. Distortions of the local structure in the PSW‐PT system were modeled also by density functional theory calculations. The obtained magnitudes of local Pb displacements coincide with the temperature of paraelectric transitionT&Vegr;,max. © 2003 American Institute of Physics