A study the breeding biology of four species of swifts, the White-collared (Streptoprocne zonaris), White-chinned (Cypseloides cryptus), Spot-fronted (Cypseloides cherriei), and Chestnut-collared (Cypseloides rutilus) Swifts, at a site in the canyon of the Río Tiribí, at ca. 1900 m on the southwest slope of Volcán Irazú in central Costa Rica, from 1984 to 1987. Observations and specimen data on these species and the Black Swift (Cypseloides niger) enabled a review of the morphology, flight, foraging, roosting, and reproduction biology of swifts of the subfamily Cypseloidinae in Costa Rica.