Three different sorts of bifacial tools-by-products of the shaping process, cores, and long use-life tools-are used to consider the role mobility plays in producing variability in hunter-gatherer lithic technologies. The relations among tool roles, raw-material distribution, and mobility as well as the archaeological consequences of the different roles are key factors. An examination of temporal trends in the use of bifacial implements in the Carson Sink of western Nevada shows how the proposed perspective on lithic technology can help to elucidate change in mobility strategies. A shift from the use of bifaces as cores to an infrequent use of bifaces as tools suggests a shift from logistical to short-term residential use of the raw-material-poor Carson Sink; a later shift to the use of small, frequently unifacial, nonresharpenable points may indicate a shift to target-specific hunting strategies.