Elfin Forest is an unincorporated residential community of San Diego County, in the foothills of the Santa Rosa Mountains. The quiet grouping of homes is southwest of Escondido and according to the USGS it is located at 33°04′25″N 117°09′51″W in the Escondido zip code of 92029. It borders the rural, unincorporated town of Harmony Grove to the northeast, San Marcos to the north and west, Olivenhain to the southwest, and Rancho Santa Fe to the south.