  We study a localized spin coupled to an Anderson impurity to model the
situation found in higher transition metal or rare earth compounds like e.g.\
LaMnO$_3$ or Gd monopnictides. We find that, even for large quantum numbers of
the localized spin, quantum fluctuations play an essential role for the case of
ferromagnetic coupling between the spin and the impurity levels. For
antiferromagnetic coupling, a description in terms of a classical spin is
appropriate.
