A luminaire mounting system can accommodate mounting a luminaire to different structures. The luminaire can comprise an adapter, which may be formed into or otherwise associated with a frame of the luminaire, for example. The adapter can provide a mechanical interface to different brackets that are configured for mounting to different structures. The adapter can connect to a first type of bracket that is configured for mounting to a vertically extending pole, to a second type of bracket that is configured for mounting to a horizontally extending pole, and to a third type of bracket that is configured for mounting to a wall or other flat surface.