We report the observation of B0(s)-B-bar0_s oscillations
performed by the CDF II detector using a data sample of 1 fb-1 of p anti-p
collisions at s**(1/2) = 1.96 TeV.  We measure the probability as a function
of proper decay time that the B_s decays with the same, or opposite, flavor
as the flavor at production, and we find a signal for B0(s)-B-bar0_s
oscillations.  The probability that random fluctuations could produce a
comparable signal is 8 x 10-8, which exceeds 5 sigma significance.  We
measure Delta M_s = 17.77 +/- 0.10 (stat) +/- 0.07 (syst) ps-1.