Supersymmetry and gauge symmetry breaking with naturally vanishing vacuum energy

We review the construction of $N=1$ supergravity models where the Higgs and super-Higgs effects are simultaneously realized, with naturally vanishing classical vacuum energy and goldstino components along gauge-non-singlet directions: this situation is likely to occur in the effective theories of realistic string models. (Invited talk presented at SUSY--95, Palaiseau, France, 15--19 May 1995)