The Lagomorph Index, a calculation of the relative proportions of cottontail rabbits and jackrabbits, is one of the most widely used analytical tools in Hohokam zooarchaeology. It is only a useful tool, however, if it has a clearly understood relationship to phenomena of archaeological interest. This is not the case, since a variety of social, economic, and environmental factors can affect values of the Lagomorph Index. Using a large database of Hohokam faunal assemblages, this study examines the influence of local vegetation, prehistoric dietary needs, and hunting methods on the Lagomorph Index. Any or all of these factors can affect index values. Independent data must be used to establish which of the many possible influences is primarily responsible for the values of the Lagomorph Index at a particular site.