We found the first documented wild nest of a Coral-billed Ground Cuckoo (Carpococcyx renauldi) at Khao Yai National Park, Thailand in June 2007. The large stick nest was monitored for 24 days including 1095 hrs of video footage; it contained two eggs and was in dense vegetation 4.85 m above the ground. Nest attentiveness of adults was almost constant with both birds taking turns to incubate or brood. Food delivered to nestlings included lizards, nestlings, a snake, frogs, earthworms, and other invertebrates. Nest defense was observed against several known nest predators but the nest ultimately failed due to predation by a pig-tailed macaque (Macaca nemistrina). These observations provide insight into the breeding ecology of the only two congeners, C. viridis and C. radiceus, for which little is known of their ecology and both are endangered.