The examination of stone-tool edges for blood-antigen residue is a relatively new technique in the archaeological analysis of lithic material. To date, a number of different methods have been employed to determine the species of origin of residual blood, such as Ouchterlony double-diffusion (Ouchterlony 1968) and radioimmunoassays (RIAs) (Lowenstein 1985, 1986). These techniques have been of limited use due to problems of sensitivity, cost, and applicability to archaeological field conditions. Enzyme immunoassays (EIAs) utilizing a nitrocellulose protein-binding membrane have shown that it is possible to retain both specificity and sensitivity in a technique that can endure the rigors of archaeological field work and the vicissitudes of differential preservation (Tersak and Hyland 1988). However, due to cross-reactivity, species identification of blood residue using immunological techniques can be problematic when it is necessary to distinguish individual species within a single genus or family. Recent work has shown that careful refinement of antisera can eliminate cross-reactivity, thereby increasing specificity (Berkeley Antibody Company, personal communication 1987). This refinement is accomplished by absorbing any antibodies from the antisera that may cross-react with antigenic sites held in common by closely related species. The ramifications of the successful implementation of this technique are discussed in terms of Paleoindian artifact function as well as paleoeconomic, paleoenvironmental, and paleodietary reconstruction using a case study from the Shoop site in central Pennsylvania.