  Experimental searches for supersymmetry are entering a new era. As future
experiments explore the mass range above the current lower bounds on
superpartner masses, a failure to observe signals of superpartner production
will begin to erode the central motivation for supersymmetry at the weak scale.
In this article we present a detailed examination of which regions of
supersymmetric parameter space are most natural and the extent to which
weak-scale supersymmetry becomes unnatural if no superpartners are observed at
LEP-II, the Tevatron, possible upgrades of these machines, and the LHC.
