  We consider two limiting regimes, the large-spin and the mean-field limit,
for the dynamical evolution of quantum spin systems. We prove that, in these
limits, the time evolution of a class of quantum spin systems is determined by
a corresponding Hamiltonian dynamics of classical spins. This result can be
viewed as a Egorov-type theorem. We extend our results to the thermodynamic
limit of lattice spin systems and continuum domains of infinite size, and we
study the time evolution of coherent spin states in these limiting regimes.
