A mirror, in particular for a microlithographic projection exposure apparatus, has an optically effective surface, a mirror substrate (205, 305), a reflection layer (220, 320), which is configured to provide the mirror with a reflectivity of at least 50% for electromagnetic radiation with a predetermined operating wavelength incident on the optically effective surface (200a, 300a) at angles of incidence in relation to the respective surface normals of at least 65°, and a substrate protection layer (210, 310) which is arranged between the mirror substrate (205, 305) and the reflection layer (220, 320). The substrate protection layer has a transmission of less than 0.1% for EUV radiation.