Although use-wear analysis of prehistoric stone tools using conventional microscopy has proven useful to archaeologists interested in tool function, critics have questioned the reliability and repeatability of the method. The research presented here shows it is possible to quantitatively discriminate between various contact materials (e.g., wood, antler) using laser scanning confocal microscopy in conjunction with conventional edge damage data. Experiments with replica and prehistoric tools suggest the quantitative method presented here provides valid functional inferences and is flexible enough to accommodate other relevant sources of data on tool function.