We present a summary of the results of an explicit calculation of the
strength of non-perturbative interactions in matrix models and string effective
Lagrangians. These interactions are induced by single eigenvalue instantons in
the d=1 bosonic matrix model. A well defined approximation scheme is used to
obtain induced operators whose exact form we exhibit. We briefly discuss the
possibility that similar instantons in a supersymmetric version of the theory
may break supersymmetry dynamically.Comment: Latex document, 17 pages, preprint CERN-TH.7356/94, UPR-620
