We describe morphological measurements, breeding biology, roost-site characteristics, and diet of the endemic and threatened Bearded Screech-Owl (Megascops barbarus) in the central highlands of Chiapas, Mexico. The first nest recorded for this species was in a natural cavity of an old oak (Quercus laurina) and contained a single nestling. Four roosting sites were located, two in Clethra chiapensis (evergreen broadleaf) and two in Pinus ayacahuite (pine; mean height  =  3.4 m). Fecal analysis indicated that diet was primarily insectivorous, consisting of Melononthidae (Coleoptera; 72.3%), along with a few Orthoptera (9.2%), Lepidoptera (3.1%), and Arachnida (1.5%). Data from 39 owls (24 captured and 15 skins) were used for morphology analysis. This species exhibited reversed sexual dimorphism, with females having greater mass and longer tails than males. Molting occurred during the rainy season (July to October), with the primary and secondary feathers being molted simultaneously. Subcutaneous fat was moderate to abundant in the dry season only (December to May). Maximum longevity we recorded was at least 4.17 yr. These first natural history data for the species provides preliminary information for understanding the ecological requirements of the Bearded Screech-Owl in fragmented tropical montane forest.