The marine invertebrates recovered from prehistoric site CA-SDi-48 were quantified using two methods, number of identified specimen (NISP) counts and minimum number of individual (MNI) estimates. The NISP counts and MNI estimates are employed to generally reconstruct the ancient environment near the site, and the ecology and behavioral activities of the aboriginal occupants of the site. It is shown that the site was occupied by a basically sedentary group of people who refined their marine invertebrate resource procurement over time to insure a maximum return for minimal effort.