  We present deep HST imaging, as well as ground-based imaging and
spectroscopy, of the optical afterglow associated with the long-duration
gamma-ray burst GRB 990712 and its host galaxy. The data were obtained 48--123
days after the burst occurred. The magnitudes of the host (R = 21.9, V = 22.5)
and optical afterglow (R = 25.4, V = 25.8, 47.7 days after the burst) favor a
scenario where the optical light follows a pure power-law decay with an index
of alpha ~ -1.0. We find no evidence for a contribution from a supernova like
SN1998bw. This suggests that either there are multiple classes of long-duration
gamma-ray bursts, or that the peak luminosity of the supernova was > 1.5 mag
fainter than SN1998bw. The HST images and EFOSC2 spectra indicate that the
gamma-ray burst was located in a bright, extended feature (possibly a
star-forming region) 1.4 kpc from the nucleus of a 0.2 L^*_B galaxy at z =
0.434, possibly a Seyfert 2 galaxy. The late-time afterglow and host galaxy of
GRB 990712 bear some resemblance to those of GRB 970508.
