  We perform a systematic analysis of soft supersymmetry breaking terms at the
one loop level in a large class of string effective field theories. This
includes the so-called anomaly mediated contributions. We illustrate our
results for several classes of orbifold models. In particular, we discuss a
class of models where soft supersymmetry breaking terms are determined by quasi
model independent anomaly mediated contributions, with possibly non-vanishing
scalar masses at the one loop level. We show that the latter contribution
depends on the detailed prescription of the regularization process which is
assumed to represent the Planck scale physics of the underlying fundamental
theory. The usual anomaly mediation case with vanishing scalar masses at one
loop is not found to be generic. However gaugino masses and A-terms always
vanish at tree level if supersymmetry breaking is moduli dominated with the
moduli stabilized at self-dual points, whereas the vanishing of the B-term
depends on the origin of the mu-term in the underlying theory. We also discuss
the supersymmetric spectrum of O-I and O-II models, as well as a model of
gaugino condensation. For reference, explicit spectra corresponding to a Higgs
mass of 114 GeV are given. Finally, we address general strategies for
distinguishing among these models.
