Fermionic coordinates and supersymmetry in quantum mechanics

We describe the quantum mechanics of particles with fermionic degrees of freedom, both in the Schroedinger wave function and Feynman path integral formalism. In particular we derive an exact expression for fermionic path integrals in (0 + 1) dimensions. Under suitable circumstances the theories we consider can exhibit supersymmetry. As an application we analyze in detail how the spontaneous breaking of supersymmetry, occurring in certain models recently discussed by Witten, can be derived as an instanton effect in the path integral formalism. (orig.)