The breeding biology of the Crescent Honeyeater Phylidonyris pyrrhoptera was studied between 1994-98 (intensively in 1996 and 1997) at Wilsons Promontory National Park. Crescent Honeyeaters commonly occurred in wet forest and dry forest habitats, but were uncommon in Saw Banksia woodland and rarely observed in closed heathland. They were found to breed only in wet forest habitats. Pairs were present at a study site in wet forest on Mt Oberon throughout the year, whereas a pair that bred in a King Fern swamp in two successive breeding seasons appeared to abandon the site in between bouts of breeding. The breeding season, extending over three months, appears unusually short for an Australian honeyeater. Within that period some pairs were multi-brooded (i.e. re-nested after a successful breeding attempt). The breeding biology of the Crescent Honeyeater was found to be generally similar to that reported for other honeyeaters in spite of marked sexual dichromatism and dimorphism (clutch size 2.8 ± 0.4 eggs, n = 28 clutches, incubation period 13.2 ± 0.2 days, n = 5 clutches, nestling period 13.0 days, n = 9 clutches). The plumage of nestlings was found to be sexually dichromatic. Fledglings of both sexes were re-sighted at the natal site in subsequent years.