We report the discovery of a 50,000 year old birch tar hafted flint tool, found off the present day coastline of the Netherlands. The production of adhesives and multi-component tools are regarded as complex technologies and take a prominent place in discussions about the evolution of human behavior. This find provides evidence on the technological capabilities of Neandertals, and illuminates the currently debated conditions under which these technologies could be maintained. 14C-AMS dating and the geological provenance of the artifact firmly associates it with a host of Middle Paleolithic stone tools and a Neandertal fossil. The find was analyzed using py-GC/MS, μ-CT and optical light microscopy. The object is a piece of birch tar, encompassing one third of a flint flake. This find is the first from northwestern Europe and complements a small set of well-dated and chemically identified adhesives from Middle Paleolithic/Middle Stone Age contexts. Combined with data from experiments and other Middle Paleolithic adhesives we demonstrate that Neandertals routinely mastered complex adhesive production strategies and composite tool use at the northern edge of their range. Large population size is therefore not a necessary condition for complex behavior and technology. The mitigation of ecological risk, as demonstrated by the challenging conditions during MIS 4 and 3, provides a better explanation for the transmission and maintenance of technological complexity.