  Using data collected in the region of the Upsilon(4S) resonance with the CLEO
II detector operating at the Cornell Electron Storage Ring CESR, we present the
first observation of B mesons decaying into the charmed strange baryons Xi_c0
and Xi_c+. We find 79 +/- 27 Xi_c0 and 125 +/- 28 Xi_c+ candidates from B
decays, leading to product branching fractions of BR(Bbar -> Xi_c0 X)BR(Xi_c0
-> Xi- pi+) = (0.144 +/- 0.048 +/- 0.021) x 10^-3 and BR(Bbar -> Xi_c+
X)BR(Xi_c+ -> Xi- pi+ pi+) = (0.453 +/- 0.096 +0.085-0.065) x 10^-3.
