  In the Minimal Supersymmetric Standard Model (MSSM), the scale $M_{SUSY}$ of
soft supersymmetry breaking is usually {\em assumed} to be of the order of the
electroweak scale. We reconsider here the possibility of treating $M_{SUSY}$ as
a dynamical variable. Its expectation value should be determined by minimizing
the vacuum energy, after including MSSM quantum corrections. We point out the
crucial role of the cosmological term for a dynamical generation of the desired
hierarchies $m_Z, M_{SUSY} << M_P$. Inspired by four-dimensional superstring
models, we also consider the Yukawa couplings as dynamical variables. We find
that the top Yukawa coupling is attracted close to its effective infrared fixed
point, corresponding to a top-quark mass in the experimentally allowed range.
As an illustrative example, we present the results of explicit calculations for
a special case of the MSSM.
