  We study the phenomenology of a class of models describing modular invariant
gaugino condensation in the hidden sector of a low-energy effective theory
derived from the heterotic string. Placing simple demands on the resulting
observable sector, such as a supersymmetry-breaking scale of approximately 1
TeV, a vacuum with properly broken electroweak symmetry, superpartner masses
above current direct search limits, etc., results in significant restrictions
on the possible configurations of the hidden sector.
