  We perform a systematic analysis of the soft supersymmetry-breaking terms
arising from four-dimensional strings. The analysis does not assume any
specific supersymmetry-breaking mechanism but provides a means of parametrizing
our ignorance in a way consistent with some known properties of
four-dimensional strings. We introduce a {\it goldstino angle} parameter
$\theta $ which says where the source of supersymmetry-breaking resides, either
predominantly in the dilaton sector ($sin \theta =1$ limit) or in the rest of
the chiral fieds, notably the moduli ($sin\theta =0$ limit). All formulae for
soft parameters take particularly simple forms when written in terms of this
angle. The $sin\theta =1$ limit is (up to small corrections) universal. As
$sin\theta $ decreases, the model dependence increases and the resulting soft
terms may or may not be universal, depending on the model. General expressions
for the soft terms as functions of $\theta$ for generic four-dimensional
strings are provided. For each {\it given} string model, one trades the four
soft parameters ($M,m,A,B$) of the minimal supersymmetric standard model by the
two parameters $m_{3/2}$ (gravitino mass) and $sin\theta $. The role of complex
phases and the associated constraints from limits on the electric dipole moment
of the neutron are discussed. It is also emphasized the importance of treating
the problem of the cosmological constant in a self-consistent manner.
