  The energy and electric field dependence of pulse shape discrimination in
liquid xenon have been measured in a 10 gm two-phase xenon time projection
chamber. We have demonstrated the use of the pulse shape and charge-to-light
ratio simultaneously to obtain a leakage below that achievable by either
discriminant alone. A Monte Carlo is used to show that the dominant fluctuation
in the pulse shape quantity is statistical in nature, and project the
performance of these techniques in larger detectors. Although the performance
is generally weak at low energies relevant to elastic WIMP recoil searches, the
pulse shape can be used in probing for higher energy inelastic WIMP recoils.
