  In the minimal supersymmetric standard model, the three gauge couplings
appear to unify at a mass scale near $2 \times 10^{16}$ GeV. We investigate the
possibility that intermediate scale particle thresholds modify the running
couplings so as to increase the unification scale. By requiring consistency of
this scenario, we derive some constraints on the particle content and locations
of the intermediate thresholds. There are remarkably few acceptable solutions
with a single cleanly defined intermediate scale far below the unification
scale.
