We report on spin-polarized electron reflection experiments in which the electron-spin motion is studied in spin-dependent quantum well structures. Oscillations of the electron-spin motion due to quantum interference are observed in the model system Cu/Co(001) both as a function of electron energy and Cu overlayer thickness. The reflectivity as well as the spin-motion data can be well interpreted in terms of a Fabry-Pérot interferometer model. In particular, this opens the possibility of studying the spin-dependent reflection properties of the buried Cu/Co interface.