  We show how R-parity can break spontaneously as a result of radiative
corrections in unified N=1 supergravity models. We illustrate this with a
concrete rank-four unified model, where the spontaneous breaking of R-parity is
accompanied by the existence of a physical majoron. We determine the resulting
supersymmetric particle mass spectrum and show that R-parity-breaking signals
may be detectable at LEP200.
