SUMMARYWideawakesSterna fuscatawere studied on Ascension between October 1957 and April 1959. As shown by Chapin, breeding in this species occurs every nine and a half months on Ascension, and two complete breeding periods were observed. Some of the birds are close to the island even in the non‐breeding period, and many settle on the breeding ground at night during the two months before breeding begins, although they suffer serious predation from cats at this time.The Wideawakes breed in dense colonies, usually on rocky ground. The single egg is incubated by the parents alternately, in shifts which on Ascension last up to six days, probably indicating that food cannot be found quickly, close to the island. The fledging period is long, but the rate of development flexible: the young can survive long periods on very little food, but grow relatively fast when given more food. In spite of this adaptation many young died of starvation in the second breeding period observed, while those which survived took longer to fledge than the chicks raised in the previous breeding period. The chicks also suffered severe predation, from frigate birds when very young and from cats when older. Together, these factors resulted in strikingly low breeding success.Individual Wideawakes on Ascension breed at intervals of 41–51 weeks, and between successive breeding periods undergo a complete moult: they finish one moult before returning to breed, but may start the next moult before their chicks are full‐grown. The length of the interval (9 months) between the start of laying in successive breeding periods appears to be determined by the time required for breeding activities, a complete moult, and an assembly and courtship period during which social stimulation is probably important.In an appendix are listed the recorded times of breeding of Wideawakes in all parts of their range: previously undiscerned six‐monthly or non‐seasonal breeding is documented for several l