  We examine recent suggestions that substructure in cold dark matter (CDM)
halos may be in conflict with the presence of thin, dynamically fragile stellar
disks. N-body simulations of an isolated disk/bulge/halo model of the Milky Way
that includes several hundred dark matter satellites with masses, densities and
orbits derived from high-resolution cosmological CDM simulations indicate that
substructure at $z=0$ plays only a minor dynamical role in the heating of the
disk over several Gyrs. This is because the orbits of satellites in present-day
CDM halos seldom take them near the disk, where their tidal effects are
greatest. Unless the effects of substructure are very different at earlier
times, our models suggest that substructure might not preclude virialized CDM
halos from being acceptable hosts of thin stellar disks like that of the Milky
Way.
