The fundamental results obtained in the past 10--15 years in studying the correlation intershell interaction in atoms are reviewed. Major attention is paid to photo processes in which the manifestations of intershell interaction have been studied both experimentally and theoretically to the greatest degree. The strong influence of multielectron shells on the few-electron shells is demonstrated with concrete examples by comparing the results of various calculations and the existing experimental data for the partial ionization cross sections, the angular distributions, and the degree of polarization of the photoelectrons. The general qualitative regularities of the manifestations of the intershell interaction and their differences n atoms with filled and unfilled shells are discussed. The processes of readjustment of the electron shells of an atom that arise from the appearance of a vacancy and their influence on he intershell interaction are examined. The literature is covered to April 1986.