  The properties of three-jet events with total transverse energy greater than
320 GeV and individual jet energy greater than 20 GeV have been analyzed and
compared to absolute predictions from a next-to-leading order (NLO)
perturbative QCD calculation. These data, of integrated luminosity 86 pb^-1,
were recorded by the CDF Experiment for proton-antiproton collisions at
sqrt{s}=1.8 TeV. This study tests a model of higher order QCD processes that
result in gluon emission and can be used to estimate the magnitude of the
contribution of processes higher than NLO. The total cross section is measured
to be 466 +/- 3(stat.)^{+207}_{-70}(syst.) pb. The differential cross section
is furthermore measured for all kinematically accessible regions of the Dalitz
plane, including those for which the theoretical prediction is unreliable.
While the measured cross section is consistent with the theoretical prediction
in magnitude, the two differ somewhat in shape in the Dalitz plane.
