To assess long-term changes in the population status of breeding Ammodramus maritimus (Seaside Sparrow) in Rhode Island, we repeated surveys conducted in 1982 by Stoll and Golet (1983). In June and July of 2007 and 2008, we surveyed 19 of Rhode Island's largest salt marshes. Seaside Sparrow abundance had declined at 9 of 11 marshes where the species was present in 1982, and we detected no sparrows at 4 smaller (<20 ha) marshes where they were present in 1982. Seaside Sparrow abundance increased at 3 marshes, including 1 at which the birds were not detected in 1982. We used aerial photographs to quantify changes in marsh size and human development within 150-m and 1-km buffers surrounding each marsh. From 1981 to 2008, the overall average number of structures within the 150-m and 1-km buffers increased by 37% and 66%, respectively. Concomitantly, salt-marsh area decreased by an overall average of 11%. Seaside Sparrow abundance was related to marsh size, but our analyses did not detect a statistical relationship of landscape or habitat-loss variables with the decline in sparrows. The Seaside Sparrow is currently classified as a species of concern in Rhode Island. However, given the population decline we documented, and the impending threat to salt-marsh habitats imposed by rising sea levels, we suggest that the classification be reassessed now and periodically in the future, and that monitoring efforts for the species be continued.