Since 1980, along the Pacific coast of North America, the population of the Caspian Tern (Hydroprogne caspia) has more than doubled in size (Survan et al. 2004), and the species’ range has been steadily expanding north (Gill and Mewaldt 1983). The Caspian Tern first reached southeast Alaska in 1981 (Gibson and Kessel 1992), and two years later it was recorded in south-central Alaska with the sighting of two birds in eastern Prince William Sound (Iselib and Kessel 1989). Caspian Terns have long been suspected of breeding in the Prince William Sound/Copper River delta area, but despite annual observations of the species, including increasing numbers of hatching-year birds and systematic surveys by boat and small plane (Bishop 1999, 2002), nesting in the region has previously gone unconfirmed. Here we report the first nesting of Caspian Terns in south-central Alaska on the Copper River delta and the species’ largest nesting colony in Alaska.