  We review the possible sources of ionizing photons within the Local Group.
Throughout most of the LG volume, the cosmic background radiation will
dominate, but locally (e.g., within d\sim 100 kpc of the Galactic disk) stellar
ionizing photons escaping from galaxies may dominate. The magnitude of the
cosmic ionizing background should be determined in the very near future by
observations of H alpha emission from the outer neutral hydrogen disks of
late-type spirals. The detection of the Magellanic Stream in H alpha suggests
that a few percent of the ionizing photons produced in the Galaxy escape the
disk. Neither a warm Local Group corona nor decay photons from a neutrino halo
can explain the Stream emission.
