  We present 18 spectra, obtained with the Keck 10m telescope, of faint field
galaxies (19 $<$ I $<$ 22, 0.2 $<$ z $<$ 0.84) previously imaged by {\it HST's}
WFPC2. Though small, our sample appears to be representative of field spirals
with a magnitude--limit of I $\le$ 22. Combining the results from the spectral
and imaging data, we have derived various quantitative parameters for the
galaxies, including colors, inclinations, emission line equivalent widths,
redshifts, luminosities, internal velocity information and physical scale
lengths. In particular, disk scale lengths (with sizes ranging from $\sim$1--5
kpc) have been measured from fits to the surface brightness profiles. We have
also measured internal velocities with a rest frame resolution of $\sigma$ = 55
to 80 km s$^{-1}$ by fitting to the emission lines. The luminosity--disk size
and luminosity--internal velocity (Tully--Fisher) relations for our moderate
redshift galaxies are similar to the scaling relations seen for local galaxies,
albeit with a modest brightening of $\sim$1 magnitude. The one bulge--dominated
galaxy in our sample (at z = 0.324) has a relatively blue color, reveals weak
emission lines and is $\sim$0.5 magnitude brighter in the rest frame than
expected for a passive local elliptical. Our data suggest that galaxies at
about half the age of the Universe have undergone mild luminosity evolution to
the present epoch, but are otherwise quantitatively similar to galaxies seen
locally.
