A general discussion of the shielding and antishielding effects of nuclear quadrupole moments for ions and at0mi.c states is presented. Values of the ionic antishielding factor y m have been obtained for the following ions: P, Inw, BiS+, and Am=. The hexadecapole antishielding factor qm has been evaluated for the case of Ins+. The general properties of the atomic correction factor R are also discussed. Values of R have been calculated for several atomic states, and were found to be in reasonable agreement with experiment.