Little is known about the breeding ecology of Hook-billed Kites (Chondrohierax uncinatus). This is the first study in Belize on this highly specialized, secretive, and uncommon Neotropical raptor species, which is showing a decreasing population trend according to the International Union for the Conservation of Nature. We monitored six Hook-billed Kite nesting attempts over a 3-yr period (2012–2014), presumably all involving the same pair nesting at a single location in the Cayo District of Belize, Central America. For each nesting attempt, we documented phenology, nest and nest-site characteristics, incubation and nestling periods, productivity, and diet. Of the six nests where eggs were observed, three had two eggs. Fledging production averaged 1.7 ± 0.5 (SD) young per nesting attempt. The male and female equitably shared incubation roles (male = 49%, female = 51%) and hunted to feed themselves during the incubation period, which is uncommon in raptors. The nestling period ranged from 20–27 d between 3 May and 18 October. Fledging coincided with or occurred after the onset of the wet season. Prey delivered to the nests comprised two species of arboreal land snails: Orthalicus princeps (99%) and Euglandina ghiesbreghti (1%). Three of the six nesting attempts occurred consecutively in 2014 and produced a combined total of five fledglings (first and third attempts fledged two young and second attempt fledged one young). This represents the first observation of successful triple brooding among Hook-billed Kites during a single breeding season. Triple brooding rarely occurs among raptors and more typically follows early nesting failure. Understanding the basic breeding biology of Hook-billed Kites is important given their highly specialized ecology, which makes them especially vulnerable to climate change and habitat loss.