  We present deep photometry obtained with the Hubble Space Telescope (HST) in
a field in Baade's Window in the Galactic bulge. We derive a luminosity
function down to I ~ 24.3, or V ~ 27.5, corresponding to M ~ 0.3 Msun. The
luminosity function from the turnoff down to this level appears remarkably
similar to that observed in the solar neighborhood. We derive a mass function
using both an empirical local mass-luminosity relation and a mass-luminosity
relation from recent stellar model calculations, allowing for the presence of
binaries and photometric errors. The mass function has a power law form with
dN/dM proportional to M^{-2.2} for M >~ 0.7 Msun. However, we find strong
evidence for a break in the mass function slope around 0.5-0.7 Msun, with a
significantly shallower slope at lower masses. The value of the slope for the
low masses depends on the assumed binary fraction and the accuracy of our
completeness correction. This mass function should directly reflect the initial
mass function.
