  We present an N=1 superfield formulation of supersymmetric gauge theories
with a compact extra dimension. The formulation incorporates the radion
superfield and allows to write supersymmetric theories on warped gravitational
backgrounds. We apply it to study the breaking of supersymmetry by the F-term
of the radion, and show that, for flat extra dimensions, this leads to the same
mass spectrum as in Scherk-Schwarz models of supersymmetry breaking. We also
consider scenarios where supersymmetry is broken on a boundary of a warped
extra dimension and compare them with anomaly mediated models.
