  We compute quadratically divergent supergravity one-loop effects on soft
supersymmetry-breaking parameters and the $\mu$ term in generic hidden sector
supergravity models. These effects can significantly modify the matching
condition for soft parameters at the Planck scale and also provide several new
sources of the $\mu$ term which are naturally of order the weak scale. We also
discuss some phenomenological implications of these effects, particularly the
violation of the scalar mass universality which may lead to dangerous FCNC
phenomena, and apply the results to superstring effective supergravity models.
