Abstract. Recent advances in interpreting the most accurate to-date measurement of atomic parity violation in Cs are reviewed. The inferred nuclear weak charge, QW ( 133 Cs) = −72.65(28)expt(36) theor , agrees with the prediction of the standard model at 1 σ level. Further improved interpretation is limited by an accuracy of solving basic correlation problem of atomic structure. We report on our progress in solving this problem within the relativistic coupled-cluster formalism. We include single-, double-and triple-electronic excitations in the coupled-cluster expansion. Numerical results for energies, electric-dipole matrix elements, and hyperfine-structure constants of Cs are presented.PACS. 32.80.Ys Weak-interaction effects in atoms -31.15.Dv Coupled-cluster theory -32.10.Fn Fine and hyperfine structure -32.70