In some portions of their range, Mexican Spotted Owls (Strix occidentalis lucida) are found occupying conifer-dominated forests, whereas in other portions of their range, they occupy narrow and steep-walled canyons. Although the characteristics of this owl's nesting and roosting habitat have been studied extensively in predominately forested environments, there is far less information describing microhabitat features associated with nesting and roosting sites in canyon systems. In this report, we quantitatively describe microhabitat characteristics of nest and roost sites of Mexican Spotted Owls within the Guadalupe Mountains of southeastern New Mexico and west Texas, where Spotted Owls dwell primarily in narrow, rocky, and semiarid canyons. We measured 21 habitat features describing the geomorphology of the canyon and finer-scaled variables at accessible owl nest or roost sites (n  =  10) and at nearby random sites up- (n  =  10) and down-canyon (n  =  10); we found that tree canopy cover (%) was significantly higher at nest and roost sites than at down-canyon random sites, and percent cover of saplings and rocky debris was significantly (P < 0.05) greater at nest and roost sites than at up-canyon and down-canyon random sites. Our findings matched some of the results of previous studies conducted in canyonlands in Utah, Arizona, and Colorado but also differed in some respects.