The degree to which Least Terns (Sterna antillarum) exhibit year-to-year fidelity to particular colony sites, as well as fidelity toward their natal colony sites, was examined using banding recoveries obtained in California. Individuals had high rates of return to colony sites where they had nested during the preceding year; of those few birds that switched colony sites between successive years, most moved only short distances from the previous area. Least Terns also showed a significant tendency toward nesting at their natal colony site. These results suggest that the species may be more philopatric than has been postulated previously, and that long-term protection and management of current colony sites is therefore an important conservation goal.