Modern studies of site distribution, utilization of near-coastal riverine resources, and the development of cultural complexity during the Holocene in southwestern Washington are hampered by the limited amount of data from previous archaeological investigations. This study of Willapa River Valley archaeology provides a context in which to interpret southern Northwest Coast near-coastal pre-contact archaeological sites. Three areas for investigation became evident during the initial research phase and directed subsequent inquiries. The first dealt with prehistoric site distribution in the Willapa region landscape, the potential for locating sites, and site distribution patterns on the Willapa River Valley alluvial terraces. Bayesian GIS modeling and geomorphologic-based survey techniques identified a new sample of 26 localities representing approximately 10,000 years of occupation. Eustatic sea level rise, seismic movement, tsunamis, and fluvial processes formed the Willapa region's landscape, and promoted natural redox reaction formation processes within submerged archaeological contexts. The second involved the pre-contact utilization of lithic, floral, and faunal natural resources, and how these adaptations relate to what we know from past work at coastal-adjacent midden sites. Excavation at the Forks Creek terrace site revealed a detailed chronology of a 2700 BP Willapa River Valley camp oriented toward the seasonal hazelnut, bitter cherry, elk, deer, and salmon resources of a fire-maintained prairie 'garden' and the Willapa River. Microblades were manufactured for their technological qualities, illustrating similarities to Salish Sea 'Locarno Beach' assemblages. The third encompassed the archaeology of the Athabaskan Kwalhioqua, and addressed the potential for recognizing cultural enclaves in the archaeological record through the study of exotic obsidian and blueschist artifacts. Obsidian 'wealth blades,' blueschist clubs, and nephrite adze artifacts define a pattern of late prehistoric long-distance trade and exchange. The 'Pacific Athabaskan coastal trade network' hypothesis poses that direct sea-going canoe trade occurred between Athabaskan cultures of the southern Northwest Coast within a counter-seismic ceremonial dance network prior to the great earthquake of AD 1700. New insights into the prehistory of the Willapa River Valley are provided with consideration given to site location, age of occupation, cultural landscapes, and the position of the Willapa River Valley prehistoric occupation within the Pacific Northwest.