  By studying p-p collisions we hope to improve our understanding of the
fundamental constituents of matter and how they form into colorless objects.
Measurements of the inclusive jet cross-sections and fragmentation properties
have confirmed that QCD based calculations give a good description of the hard
scattering processes. However, as our analysis of jets has improved it has
become clear that there is significant contribution to these measurements from
processes other than those directly related to the initial hard scattering -
the so-called underlying event. Several processes contribute to the underlying
event, namely the beam-beam remnants, initial and final state radiation and
multiple parton interactions. The structure of the jet and the underlying event
are strikingly different in both their particle compositions and momentum
distributions. Only by understanding both components can one fully describe a
p-p collision. I will discuss preliminary results from studies of the
underlying event in p-p collisions at sqrt(s) = 200 GeV at RHIC, and compare to
PYTHIA predictions, as well as earlier results from the Tevatron at 1.8-1.96
TeV.
