We conducted a census of Wedge-tailed Shearwaters breeding at D’Arros Island and nearby St Joseph Atoll in the Amirantes Islands, Seychelles, to assess potential changes in population size and provide data for future review of St Joseph Atoll as an Important Bird Area (IBA). After identifying all active colony areas on D’Arros Island and within the atoll, we used a combination of direct counts and areabased estimates to determine breeding population size. We estimated that during the 2009/10 breeding season, 254 (95% CI 234–279) pairs of Wedge-tailed Shearwaters initiated nests on D’Arros Island, and 28 655 (95% CI 22 853–36 302) pairs nested on islands within St Joseph Atoll. The number of breeding pairs at the largest colony was similar to estimates from a census conducted in 2002, and the total breeding population within St Joseph Atoll was determined to be the third largest breeding location in the western Indian Ocean, accounting for 16% of the regional population. The results presented here support the assertion that St Joseph Atoll qualifies as an IBA under several criteria and help to demonstrate that the large numbers of Wedge-tailed Shearwaters breeding in St Joseph Atoll have remained fairly consistent over a seven-year period.