  QED corrections to the $g$ factor of Li-like and B-like ions in a wide range
of nuclear charges are presented. Many-electron contributions as well as
radiative effects on the one-loop level are calculated. Contributions resulting
from the interelectronic interaction, the self-energy effect, and most of the
terms of the vacuum-polarization effect are evaluated to all orders in the
nuclear coupling strength $Z\alpha$. Uncertainties resulting from nuclear size
effects, numerical computations, and uncalculated effects are discussed.
