  We review the various techniques used to constrain the Galactic halo mass
profile for radii > 20 kpc with particular emphasis on identifying a
self-consistent halo model and resolving the apparent discrepancies present in
the literature on this subject. We collate published results and demonstrate
that they are all consistent with a Galactic halo that is nearly isothermal
with a characteristic velocity of 180 to 220 km/sec and an extent >~ 200 kpc.
