  We present the first observation in hadronic collisions of the electroweak
production of vector boson pairs (VV; V = W,Z) where one boson decays to a
hadronic final state. The data correspond to 3.5/fb of integrated luminosity
collected by the CDF II detector in p-pbar collisions at a center-of-mass
energy of 1.96 TeV. Event selection requires two identified jets and large
transverse momentum imbalance. The analysis employs several novel techniques to
suppress multijet background and reduce systematic uncertainties. We observe
1516 +/- 239(stat) +/- 144(syst) diboson candidate events and measure a cross
section of sigma(ppbar to VV+X) = 18.0 +/- 2.8(stat) +/- 2.4(syst) +/-
1.1(lumi) pb, in agreement with standard model expectations.
