Full text can be accessed at http://www.tandfonline.com/doi/full/10.1080/0067270X.2011.647952Stone tools have a critical role to play in our understanding of the behavior of early humans. In particular, the types of raw materials that are present in stone tool assemblages, and the sources from which they are acquired, provide information relating to decision-making processes, planning, the organisation of technology and group mobility. The characterisation of Stone Age lithic artefact assemblages from two rockshelter sites in southern Tanzania, Magubike and Mlambalasi, allowed for the evaluation of inter- and intra-assemblage variability. Raw material characterisation was conducted using macroscopic and microscopic analyses. Numerous raw material sourcing studies have been undertaken on Stone Age lithic assemblages recovered from sites in Tanzania and the rest of East Africa. Generally, these studies have concentrated on identifying the sources of a particular type of stone raw material, such as chert, obsidian and basalt; however, the attributes of the whole assemblage have only rarely been examined. Furthermore, few archaeologists describe stone materials in terms of their basic petrographic characteristics. Both of these weaknesses are the direct result of the lack of a standardised methodology for describing lithic raw materials. This thesis therefore outlines a strategy for raw material sourcing, with a focus on description and grounded in geoarchaeological theory. When combined with typological and technological analyses, the results of the raw material analyses suggest the exclusive use of locally acquired stone