Technological and typological studies of the chipped-stone industries of Palaeolithic Greece have hitherto been founded upon thorough descriptions of the morphological attributes of artefacts. This article departs from this tradition to examine, by means of refitting, the technology that created a group of 1691 lithic artefacts at Upper Palaeolithic Kastritsa. Refitting seeks to reconstruct individual reduction sequences by making connections between artefacts that are the results of successive steps in lithic production, thereby revealing more about the biographies of those artefacts. This approach, although extremely valuable, is not universally applicable because it is time-consuming and works only if the artefacts it examines have been retrieved from undisturbed contexts. Kastritsa's industry, however, lends itself to this sort of analysis thanks to the site's generally good spatial and temporal integrity. Attention is focused on layer 12 (in the western part of the rockshelter), a layer that has, amongst other features, yielded two sets of postholes. This evidence of habitation structures of this sort is unique in the Upper Palaeolithic record of south-east Europe. The analysis shows that this layer contains the greatest percentage of refitting specimens so far recorded at Kastritsa and makes a number of observations concerning the technological decisions taken by the knappers who worked there. It also suggests that specialised knapping and transformation activities probably took place in this part of the camp.