In SouthEast Asia and Oceania as in many other areas of the world, shelled molluscs such as clams, cockles, conchs and snails provide multiple services for coastal livelihoods (e.g. food security, water purification, stabilization of the shoreline and habitat structure, etc.). On Atauro Island (Timor-Leste) discarded shells resulting from human activities are found on the coastal shore as well as at the top of Atauro mountains, both at the soil surface and buried in the substrate. Nowadays, shelled molluscs provide a source of nutritious food, income and inspiration to local communities. In total, 67 species of molluscs were found to be used in Atauro Island for multiple purposes. Women and children played an important role gathering, processing and selling molluscs. Indeed, in order to efficiently harvest shells local shellfishers must have accurate knowledge regarding the diversity, habitat and distribution of molluscs, as well as constantly learn new information on the dynamics of local fisheries and the marine environment. In a world where ecosystems and societies are facing major challenges such as climate change and ecological services degradation, the link between local knowledge and academic science is central for sustainable development. Drawing from our research in Atauro Island (Timor-Leste), the aim of this paper is 1) to illustrate the diversity of practices and local knowledge involved in the gathering of molluscs; and 2) to identify socio-cultural and ecological factors that affect the way local people interact with molluscs and the marine environment. We found that the relationship between humans and molluscs in Atauro offers insights to understand long-term socio-ecological changes on the island. Our results allow us to propose lines of action to monitor, assess and manage molluscan fisheries in Timor-Leste while combining traditional and scientific knowledge.