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(1) The floral biology and pollination ecology of eleven species of the pantropical genus Parkia (Leguminosae: Mimosoideae) were studied in Amazonian Brazil. Most are large forest trees. (2) The unit of pollination is a ball-like capitulum composed of many small flowers. Specialized flower types are arranged in different ways in the three taxonomic sections of the genus and this has important implications for pollination. (3) Nine species in two sections are bat-pollinated. Their floral adaptations and the mechanism of pollen transfer are similar although there are many differences in details. Individual capitula open for one night, secrete copious nectar, have distinctive smells, are bright red, or yellow, or both, and are held beyond the foliage or rarely within the crown. (4) Andromonoecy occurs in most species; several have a proportion of their capitula with all the fertile flowers functionally male, probably indicating a mechanical constraint on fruit production. Some species appear to be protandrous. (5) Eight species of bats from four subfamilies of the Phyllostomidae were caught at flowering trees. The most important pollinator is Phyllostomus discolor. Bats acting as pollinators land briefly on capitula to take pollen and nectar. In some species, a landing platform is provided by the basal fringe of elongated staminodial filaments. Some small bats take nectar on the wing without contacting the fertile flowers and thus act as nectar thieves, (6) Sympatric chiropterophilous species reduce competition for pollinators primarily by phenological separation. Different flowering strategies affect the range of bat species attracted. Vision is apparently important in the location of open capitula. (7) Non-flying mammals, hummingbirds, bees, wasps, moths, and other insects take nectar or pollen or both but none is likely to be important in the pollination of the chiropterophilous species. (8) Comparison with the pollination of Parkia by pteropodid bats in the palaeotropics emphasizes the similarities in many features. The principal difference is in the landing position of the bat. (9) One taxonomic section, whose capitula lack specialized nectar-secreting flowers, is wholly or partly entomophilous, and visited especially by trigonid bees.