  Using deep infrared observations conducted with the CISCO imager on the
Subaru Telescope, we investigate the field-corrected pair fraction and the
implied merger rate of galaxies in redshift survey fields with Hubble Space
Telescope imaging. In the redshift interval, 0.5 < z < 1.5, the fraction of
infrared-selected pairs increases only modestly with redshift to 7% +- 6% at
z~1. This is nearly a factor of three less than the fraction, 22% +- 8%,
determined using the same technique on HST optical images and as measured in a
previous similar study. Tests support the hypothesis that optical pair
fractions at z~1 are inflated by bright star-forming regions that are unlikely
to be representative of the underlying mass distribution. By determining
stellar masses for the companions, we estimate the mass accretion rate
associated with merging galaxies. At z~1, we estimate this to be 2x10^{9 +-
0.2} solar masses per galaxy per Gyr. Although uncertainties remain, our
results suggest that the growth of galaxies via the accretion of pre-existing
fragments remains as significant a phenomenon in the redshift range studied as
that estimated from ongoing star formation in independent surveys.
