  We report the first observation of single top quark production using 3.2
fb^-1 of pbar p collision data with sqrt{s}=1.96 TeV collected by the Collider
Detector at Fermilab. The significance of the observed data is 5.0 standard
deviations, and the expected sensitivity for standard model production and
decay is in excess of 5.9 standard deviations. Assuming m_t=175 GeV/c^2, we
measure a cross section of 2.3 +0.6 -0.5 (stat+syst) pb, extract the CKM matrix
element value |V_{tb}|=0.91 +-0.11 (stat+syst) 0.07(theory), and set the limit
|V_{tb}|>0.71 at the 95% C.L.
