1999 to August 2000, we conducted monthly mist netting in the Chamela-Cuixmala Biosphere Reserve, Jalisco, Mexico to document the phenology and habitat use of the Red-breasted Chat {Granatellus veniistiis). We collected information on its nesting biology during the breeding season of 2001. Chats {n = 116) were caught throughout the 18 months of the study; however, far fewer captures occurred during the dry season than during the wet season. Our capture data revealed that chats made greater use of deciduous {n = 88) than semi-deciduous forest {n = 28); there were no interactions among forest type, season, and gender. Birds in breeding condition were captured June-September and molting birds were captured August-October. We found 10 cup-shaped nests in June and July. Nests were 48-103 cm above ground in saplings <2 m high. Clutch size was 3-4 and only the female incubated. The incubation period was 14 days, and we estimated the nestling period to be approximately 8-10 days. Of eight nests found with eggs or young, three were depredated during the egg stage, three during the nestling stage, and two were successful.