  A review of the Hubble Space Telescope H0 Key Project is given, as presented
at the IAU Symposium 183 on "Cosmological Parameters" held in Kyoto, Japan in
August, 1997. An outline of the goals and progress toward this effort is given.
Cepheid distances to over a dozen galaxies have now been measured using HST.
These distances form the basis for the calibration of a number of secondary
distance indicators including the Tully-Fisher relation and type Ia supernovae.
Substantial progress has been made in placing empirical limits on the effects
of varying metal abundance on the derived Cepheid distances. The Key Project
data are consistent with a small effect of -0.24 +/- 0.16 mag/dex. The value of
the Hubble constant is presently determined to be 73 +/- 6 (statistical) +/- 8
km/sec/Mpc, based upon a number of methods. A summary of the recent calibration
of the Cepheid period-luminosity relation using Hipparcos is also given.

Astrophysics