Ecological studies suggest that rare taxa are more likely to go extinct than abundant ones, but the relationship between rarity and extinction in the fossil record has received surprisingly little attention. The purpose of this research is to examine the link between rarity (defined here to include mean abundance, spatial and temporal variability in abundance, geographic range, and habitat specificity) and extinction during both background and mass extinction intervals in the Cenozoic record of U.S. Coastal Plain mollusks. The questions I will address include: (1) Are rare taxa more likely to go extinct? (2) Does the relationship between rarity and extinction differ in mass versus background extinction intervals? and (3) Does selectivity differ according to metric of rarity? To accomplish this, I will synthesize previously processed, but unpublished, abundance, habitat, and spatial occurrence data collected by myself and colleagues, along with substantial data from the paleontological literature. This research represents one of the first attempts to explore the relationship between fossil abundance and extinction and will contribute substantially to our understanding of abundance and diversity in the Cenozoic of the U.S. Coastal Plain. collapse