  We report the discovery of pulsed X-ray emission from the compact object CXOU
J112439.1-591620 within the supernova remnant (SNR) G292.0+1.8 using the High
Resolution Camera on the Chandra X-ray Observatory. The X-ray period
(P=0.13530915 s) is consistent with extrapolation of the radio pulse period of
PSR J1124-5916 for a spindown rate of dP/dt=7.6E-13 s/s. The X-ray pulse is
single peaked and broad with a FWHM width of 0.23P (83 degrees). The
pulse-averaged X-ray spectral properties of the pulsar are well described by a
featureless power law model with an absorbing column density, N_H= 3.1E21
atoms/cm^2; photon index, gamma = 1.6; and unabsorbed 0.3-10 keV band
luminosity, L_X = 7.2E32 erg/s. We plausibly identify the location of the
pulsar's termination shock. Pressure balance between the pulsar wind and the
larger synchrotron nebula, as well as lifetime issues for the X-ray-emitting
electrons, argues for a particle- dominated PWN that is far from the minimum
energy condition. Upper limits on the surface temperature of the neutron star
are at, or slightly below, values expected from ``standard'' cooling curves.
There is no optical counterpart to the new pulsar; its optical luminosity is at
least a factor of 5 below that of the Crab pulsar.
