  We provide a study of the phenomenology of orbifold compactifications of the
heterotic string within the context of supergravity effective theories. Our
investigation focuses on those models where the soft Lagrangian is dominated by
loop contributions to the various soft supersymmetry breaking parameters. We
consider the pattern of masses that are governed by these soft terms and
investigate the implications of certain indirect constraints on supersymmetric
models, such as flavor-changing neutral currents, the anomalous magnetic moment
of the muon and the density of thermal relic neutralinos.
