Close white dwarf-red dwarf binaries must have gone through a common-envelope phase during their evolution. DE CVn is a detached white dwarf-red dwarf binary with a relatively short (~8.7h) orbital period. Its brightness and the presence of eclipses makes this system ideal for a more detailed study. From a study of photometric and spectroscopic observations of DE CVn we derive the system parameters that we discuss in the framework of common-envelope evolution.