SUMMARYSaunders, D. A. 1977. Breeding of the Long-billed Corella at Coomallo Creek, WA. Emu 77: 223–227.The breeding of the Long-billed Corelia was studied at Coomallo Creek between 1972 and 1976. During this period fifteen nests were studied and a total of twenty-eight young were fledged. Mean clutch size was 2.3 eggs and the mean size for the six eggs measured was 45.5×30.2 mm. The breeding season was found to be August to October and the incubation period twenty-four to twenty-nine days. Nine nestlings were measured and growth curves for three characters are given. The birds moved quite locally, to join birds from other nearby breeding areas and forage during the non-breeding season. Fledge-lings from Coomallo Creek left the nest with the lengths of their upper culmens within the range of that of the Little Corelia and this may be a source of confusion regarding the status of these two species in Western Australia.