Less than two decades ago, archaeologists considered lithic debitage, the flakes and debris left from the manufacture of stone tools, little more than uninformative waste. Since then, fieldworkers have increasingly recognized that stone flakes can provide information both singly and in aggregate.Many methods are now available for analyzing lithic debitage, yet no single method is entirely reliable as a vehicle to meaningful interpretation of past behavior. Part of the problem lies in the disparity between tightly controlled experimental conditions and the difficulty of sorting individual sequences out of the masses of stone found in many archaeological sites. Contributors to this volume seek to identify the strengths and weaknesses in the more widespread and competing analytical forms while arguing for the use of multiple lines of evidence. As the title indicates, their primary focus is on mass analysis of aggregates rather than individual flakes. Thus several chapters also address problems of subdividing aggregates to better deal with the "mixed assemblages" generated by multiple factors over time.