  An action principle that applies uniformly to any number N of supercharges is
proposed. We perform the reduction to the N=0 partition function by integrating
out superpartner fields. As a new feature for theories of extended
supersymmetry, the canonical Pfaffian measure factor is a result of a Gaussian
integration over a superpartner. This is mediated through an explicit choice of
direction n^a in the \theta-space, which the physical sector does not depend
on. Also, we re-interpret the metric g^{ab} in the Susy algebra [D^a,D^b] =
g^{ab}\partial_t as a symplectic structure on the fermionic \theta-space. This
leads to a superfield formulation with a general covariant \theta-space sector.
