  Single W boson production in electron-positron collisions is studied with the
L3 detector at centre-of-mass energies between 192 GeV and 209 GeV. Events with
two acoplanar hadronic jets or a single energetic lepton are selected, and the
single W cross section is measured. Combining the results with measurements at
lower centre-of-mass energies, the ratio of the measured cross section to the
Standard Model expectation is found to be 1.12^{+0.11}_{-0.10}+/-0.03. From all
single W data, the WWgamma gauge coupling parameter kappa_gamma is measured to
be 1.116^{+0.082}_{-0.086}+/-0.068.
