Abstract: We study the underlying event in proton-antiproton collisions by examining the behavior of charged particles produced in association with a large transverse momentum jet (similar to 2: 2 fb(-1)) or with a Drell-Yan lepton pair (similar to 2.7 fb(-1)) in the Z-boson mass region [70 < M(pair) < 110 GeV/c(2)] as measured by CDF at 1.96 TeV center-of-mass energy. We use the direction of the lepton pair or the leading jet in each event to define regions of eta-phi space that are sensitive to the modeling of the underlying event. The data are corrected to the particle level to remove detector effects and are then compared with several QCD Monte Carlo models.