  We perform a supergraph computation of the effective Kaehler potential at one
and two loops for general four dimensional N=1 supersymmetric theories
described by arbitrary Kaehler potential, superpotential and gauge kinetic
function. We only insist on gauge invariance of the Kaehler potential and the
superpotential as we heavily rely on its consequences in the quantum theory.
However, we do not require gauge invariance for the gauge kinetic functions, so
that our results can also be applied to anomalous theories that involve the
Green-Schwarz mechanism. We illustrate our two loop results by considering a
few simple models: the (non-)renormalizable Wess-Zumino model and Super Quantum
Electrodynamics.
