Invertebrate remains recovered during excavations on the Sepik coast of Papua New Guinea in 1996 were analyzed. The main excavations took place in the Aitape hills, ∼2 km inland from the current coastline, and on Tumleo Island, ∼3 km off the coast. Remains of 72 mollusk, one arthropod, and two echinoderm species were identified. Forty-six of these are marine, 19 are from freshwater or brackish water and mangrove habitats, and 11 are terrestrial. A complete list and figures of most species are given. Analysis of the recovered remains suggests that in the Aitape hills, mollusk species gathered in freshwater and brackish water habitats were exploited extensively, while marine species played an insignificant role as a food source. Conversely, on Tumleo Island, most freshwater species found on the mainland are absent. Only a limited number of species inhabiting the interface of salt water and freshwater, such as mangrove swamps and estuaries, are present in considerable quantities. In addition, marine species were likely to have played a larger role as a food resource. Artifacts made from invertebrate remains are described and pictured.