Home ranges of the Northern Spotted Owl (Strix occidentalis caurina) in the Pacific Northwest (Forsman et al. 1984, Solis and Gutierrez 1990, Carey et al. 1992, Zabel et al. 1995), of the Mexican Spotted Owl (S. o. lucida) in the southwestern U.S. (Ganey and Balda 1989, Zwank et al. 1994, Ganey et al. 1999), and of the California Spotted Owl (S. o. occidentalis) in the Sierra Nevada (Call et al. 1992, Zabel et al. 1992) have all been quantified. No home-range estimates exist, however, for isolated populations of the California Spotted Owl in the southern portion of its range (Gutierrez and Pritchard 1992, Gutierrez et al. 1995). Therefore, we report breeding-season home-range size for two pairs of radio-marked Spotted Owls in the San Bernardino Mountains, which support the largest population of the subspecies in southern California (LaHaye et al. 1997).