  We discuss supersymmetry breaking in the field-theoretical limit of the
strongly-coupled heterotic string compactified on a Calabi-Yau manifold, from
the different perspectives of four and five dimensions. The former applies to
light degrees of freedom below the threshold for five-dimensional Kaluza-Klein
excitations, whereas the five-dimensional perspective is also valid up to the
Calabi-Yau scale. We show how, in the latter case, two gauge sectors separated
in the fifth dimension are combined to form a consistent four-dimensional
supergravity. In the lowest order of the $\kappa^{2/3}$ expansion, we show how
a four-dimensional supergravity with gauge kinetic function $f_{1,2}=S$ is
reproduced, and we show how higher-order terms give rise to four-dimensional
operators that differ in the two gauge sectors. In the four-dimensional
approach, supersymmetry is seen to be broken when condensates form on one or
both walls, and the goldstino may have a non-zero dilatino component. As in the
five-dimensional approach, the Lagrangian is not a perfect square, and we have
not identified a vacuum with broken supersymmetry and zero vacuum energy. We
derive soft supersymmetry-breaking terms for non-standard perturbative
embeddings, that are relevant in more general situations such as type I/type
IIB orientifold models.
