The Archaeology of Tanamu 1 presents the results from Tanamu 1, the first site to be published in detail in the Caution Bay Studies in Archaeology series. In 2008-2010, the Caution Bay Archaeological Project excavated 122 stratified sites 20km northwest of Port Moresby, south coast of Papua New Guinea. This remains the largest archaeological salvage program ever undertaken in the country. Yielding well-provenanced and finely dated assemblages of ceramics, faunal remains, and stone and shell artefacts, this remarkable set of sites has extended the geographical range of the Lapita cultural complex to not only the mainland of Papua New Guinea, but more remarkably to its south coast, at Australia's doorstep. At least as important has been the discovery of rich and well-defined layers deposited up to c. 1700 years before the emergence of Lapita in the Bismarck Archipelago, providing insights into pre-ceramic cultural practices on the Papua New Guinea south coast. Sites and layers interdigitate across the Caution Bay landscape to reveal a 5000-year story, each site contributing unique details of the grander narrative. Positioned near the coast on a sand ridge, Tanamu 1 contains three clear occupational layers: a pre-Lapita horizon (c. 4050-5000 cal BP), a Late Lapita horizon (c. 2750-2800 cal BP), and sparser later materials capped by a dense ethnohistoric layer deposited in the past 100-200 years. Fine-grained excavation methods, detailed specialist analyses and a robust chronostratigraphy allows for a full and transparent presentation of data to start laying the building blocks for the Caution Bay story.