  We discuss $d=1, {\cal N}=2$ supersymmetric matrix models and exhibit the
associated $d=2$ collective field theory in the limit of dense eigenvalues.
From this field theory we construct, by the addition of several new fields, a
$d=2$ supersymmetric effective field theory, which reduces to the collective
field theory when the new fields are replaced with their vacuum expectation
values. This effective theory is Poincare invariant and contains perturbative
and non-perturbative information about the associated superstrings.
