comparison with the very characteristic microlithic and geometric arrowheads, mesolithic tools remain marginal in lithic studies. This situation is explained by its atypical attributes which limits the relevance of morphological and typological approaches. This PhD thesis proposes to redefine toolkits from a techno-functional perspective thanks to use-wear approach, with the aim of considering these objects in a more complete cycle of activities. The four main corpuses considered here are dated to the Early Mesolithic (10th-7th millennium BC) and are all located in Northern France and Belgium. The analysis of these lithic assemblages made it possible to highlight the importance of unretouched tools which constitute the majority of the objects used by the prehistoric population. This result leads us to reconsider the conclusions of the studies which only reasoning on the voluntarily modified tools. The 501 recognised use zones logically show that the mesolithic people transformed animal materials, especially the skin. Besides this, the importance occupied by vegetal craftsmanship appears as a real change in comparison with the Paleolithic. The scraping of plants and wood was probably a major activity throughout the Mesolithic period. Contrasts can be observed between settlements, probably due to different site functions. It is certain that this variability is also linked to cultural factors that may be better understood in the future thanks to an integrated approach such as that developed in this thesis. ; En comparaison avec les armatures de projectiles micro lithiques et géométriques très caractéristiques, l'outillage mésolithique reste en marge dans les études lithiques. Cette situation s'explique par son apparence peu typée qui limite la pertinence des approches morpho-typologiques. Cette thèse se propose de redéfinir l'outillage sous l'angle techno-fonctionnel par l'application de méthodes tracéologiques, dans l'objectif de replacer ces objets dans un cycle d'activités plus complet. Les quatre gisements ...