The early Weichselian period witnessed the emergence of the Northwestern technocomplex, spanning a vast geographical region from the Paris Basin to the Rhine River. This technocomplex is characterized by a unique lithic industry, with the production of flakes, points, and blades. Although these productions appear mostly contemporaneous, their representation varies across sites in northern France, where extensive excavations have been conducted through three decades of preventive archaeology, yielding numerous opened air sites and a strong understanding of the stratigraphic sequence of the region. Positioned as a crossroads between Late Middle Palaeolithic cultures of eastern central Europe and the well-documented region of southwestern France, the Northwestern technocomplex prompts inquiries into the origins of its diverse lithic industry. Indeed, some scholars posit that this unique lithic industry may be attributed to a confluence of influences resulting from successive migrations of different cultural groups responding to climatic variations. But how can we assess the footprint of different mousterian groups in one region ? Beyond the lithic components themselves, would it translate in the archaeological records in different « lifeways » regarding strategic economies and territorial behaviour ? Moreover, if those various influences can be demonstrated, would it be possible to consider the cultural structuring of Neanderthal populations of Western Europe ? Drawing upon historical methodologies employed to investigate these questions, this presentation introduces a techno-functional approach implemented in an ongoing PhD research. This approach shifts the analytical focus from emphasizing differences in productions to interrogating similarities between various products, whether retouched or not. By adopting this perspective, the research aims to shed light on the nuanced techno-economic strategies employed by Mousterian groups in the Northwestern technocomplex. Through a comparative analysis of the techno-functional aspects and considering existing knowledge about the lithic production within the technocomplex, the study seeks to enhance our comprehension of the cultural dynamics and economic strategies of the mousterian populations during the early Weichselian.