  We present results from our ongoing program to map the visual orbits of
pre-main sequence binaries in the Taurus star forming region using adaptive
optics imaging at the Keck Observatory. We combine our results with
measurements reported in the literature to analyze the orbital motion for each
binary. We present preliminary orbits for DF Tau, T Tau S, ZZ Tau, and the
Pleiades binary HBC 351. Seven additional binaries show curvature in their
relative motion. Currently, we can place lower limits on the orbital periods
for these systems; full solutions will be possible with more orbital coverage.
Five other binaries show motion that is indistinguishable from linear motion.
We suspect that these systems are bound and might show curvature with
additional measurements in the future. The observations reported herein lay
critical groundwork toward the goal of measuring precise masses for low-mass
pre-main sequence stars.
