This article investigates the degree and nature of ‘imposed form’ in Middle Palaeolithic scrapers, the most common category of stone tool produced by Neanderthals. Novice flintknappers unfamiliar with Middle Palaeolithic tool forms were found to consistently employ two rules in manufacturing scrapers: the striking platform and any adjacent blunt edges were left intact to facilitate prehension, and the longest edge with the most acute spine-plane angle was retouched. Scrapers from three major Middle Palaeolithic sites adhered to these rules in over 90 per cent of cases, but significant divergence from these rules was found in a sample from Skhul cave (Israel) level B1, associated with early anatomically modern Homo sapiens. It is concluded that Middle Palaeolithic scraper manufacture was structured by the need to create a suitable working edge, and to locate that edge to maximize ease and comfort during manufacture and use. The overall shape of the resulting tools was thus not an expression of ‘imposed form’ in the conventional sense. The discovery of violations of these rules in the Skhul B1 collection provides evidence of increased use of imposed form, as well as potentially significant behavioural differences between early anatomically modern Homo sapiens and contemporary Neanderthals.