Discusses a series of methodological issues and problems related to the development and distinctiveness of the so-called wear polishes produced by the various materials with which prehistoric stone tools come in contact. A selection of functional observations on tool use for the Upper Palaeolithic, Mesolithic, and Neolithic periods is presented. The archaeological part of the review is concerned with two trends in functional analysis, namely 1) controlled site-specific studies with different levels of foci, and 2) thematic studies of particular tool types, e.g., endscrapers, burins, and unmodified debitage. Finally, problems concerning the interpretation of hafting and of multiple tool use are discussed.