  We study the issue of radion stabilization within five-dimensional
supersymmetric theories compactified on the orbifold S^1/Z_2. We break
supersymmetry by the Scherk-Schwarz mechanism and explain its implementation in
the off-shell formulation of five dimensional supergravity in terms of the
tensor and linear compensator multiplets. We show that radion stabilization may
be achieved by radiative corrections in the presence of five-dimensional fields
which are quasi-localized on the boundaries through the presence of Z_2 odd
mass terms. For the mechanism to work the number of quasi-localized fields
should be greater than 2+N_V-N_h where N_V and N_h are the number of massless
gauge- and hypermultiplets in the bulk. The radion is stabilized in a
metastable Minkowski vacuum with a lifetime much larger than cosmological
time-scales. The radion mass is in the meV range making it interesting for
present and future measurements of deviations from the gravitational
inverse-square law in the submillimeter range.
