Holomorphy and dynamical scales in supersymmetric gauge theories

New recent results in supersymmetric gauge theories based on holomorphy and symmetry considerations are extended to the case where the gauge coupling constant is given by the real part of a chiral superfield. We assume here that its dynamics can be described by an effective quantum field theory. Then its vacuum expectation value is a function of the other coupling constants, viewed as chiral background superfields. This functional dependence can be determined exactly and satisfies highly non-trivial consistency checks.