We study the topology of hard collisions in Run 2 at CDF
using jets, dijets, and Drell-Yan lepton pairs.  The direction of
the leading jet (Midpoint algorithm, R = 0.7) or the Z-boson
(lepton pairs with 70 < M(pair) < 110 GeV) is used to define three
regions in eta-phi space: toward, away, and transverse.  We study
charged particles in the range pT > 0.5 GeV/c and |eta| < 1 and
hence each of the three regions has an area in eta-phi space of 4pi/3.
For jets the transverse region is perpendicular to the plane of the
hard 2-to-2 scattering and is therefore very sensitive to the underlying
event.  For Z-boson events both the toward and transverse regions are very
sensitive to the underlying event. The data are corrected to the particle
level and compared with PYTHIA (with multiple parton interactions) and
HERWIG (without multiple parton interactions).