  We use the three lepton and missing energy "trilepton" signature to search
for chargino-neutralino production with $2.0 fb^{-1}$ of integrated luminosity
collected by the CDF II experiment at the Tevatron $p\bar{p}$ collider. We
expect approximately 11 supersymmetric events for a specific choice of
parameters of the mSUGRA model, but our observation of 7 events is consistent
with the standard model expectation of 6.4 events. We constrain the mSUGRA
model of supersymmetry and rule out chargino masses up to $145 GeV/c^2$ for a
specific choice of parameters.
