  In searches for planetary transits in the field, well over half of the survey
stars are typically giants or other stars that are too large to permit
straightforward detection of planets. For all-sky searches of bright V<~11
stars, the fraction is ~90%. We show that the great majority of these
contaminants can be removed from the sample by analyzing their reduced proper
motions (RPMs): giants have much lower RPMs than dwarfs of the same color. We
use Hipparcos data to design a RPM selection function that eliminates most
evolved stars, while rejecting only 9% of viable transit targets. Our method
can be applied using existing or soon-to-be-released all-sky data to stars
V<12.5 in the northern hemisphere and V<12 in the south. The method degrades at
fainter magnitudes, but does so gracefully. For example, at V=14 it can still
be used to eliminate giants redward of V-I~0.95, that is, the blue edge of the
red giant clump.
