This paper investigates how coastal mobility and a community’s place within regional trade networks intersects with technological organisation. To do this we identified different types of lithic production and exchange during the late pre-colonial period at three coastal sites around Madang in northeast New Guinea. The study is the first major technological and sourcing study in this area. Consistent with terrestrial models, lithic technological analysis crucially shows that groups with higher levels of coastal mobility 1) were reducing a wider range of lithic materials, and 2) reduced material less intensively than groups with indirect access. Conversely, groups with lower coastal mobility levels 1) were flaking a restricted range of lithic materials, and 2) reduced material more intensively. Geochemical analysis, using X-ray Fluorescence, shows that at all three sites obsidian artefacts exclusively derived from Kutau/Bao (Talasea) in West New Britain. This indicates that, by about 600 years ago through to the late nineteenth century, the Kutau/Bao source had become a specialised export product, being fed into major distribution conduits operational along the northeast coast. Importantly, there is no evidence for exchange with other sources such as Admiralties or Fergusson Island obsidian. This is contrastive to the Sepik coast, where obsidian from the Admiralties Islands featured prominently alongside West New Britain obsidian, and suggests the emergence of different coastal supply lines feeding the northeast Madang coast and the north Sepik coast.