  I discuss supersymmetric extensions of the Standard Model containing an extra
U(1)' gauge symmetry which provide a solution to the mu-problem and at the same
time protect the proton from decaying via dimension 4 operators. Moreover, all
fields are protected by chirality and supersymmetry from acquiring high scale
masses. The additional requirements of anomaly cancellation and gauge coupling
unification imply the existence of extra matter multiplets and that several
fields participate in U(1)' symmetry breaking simultaneously. While there are
several studies addressing subsets of these requirements, this work uncovers
simultaneous solutions to all of them. It is surprising and encouraging that
extending the Minimal Supersymmetric Standard Model by a simple U(1) factor
solves its major drawbacks with respect to the non-supersymmetric Standard
Model, especially as current precision data seem to offer a hint to the
existence of its corresponding Z' boson. It is also remarkable that there are
many solutions where the U(1)' charges of the known quarks and leptons are
predicted to be identical to those E_6 motivated Z' bosons which give the best
fit to the data. I discuss the solutions to these constraints including some
phenomenological implications.
