Ocean acidification (OA) is already harming shellfish species in the Pacific Northwest, a global hotspot of OA. While OA poses a threat to regional communities, economies, and cultures that rely on shellfish, identified gaps remain in adaptive capacity and vulnerability of several stakeholders. This project will address these gaps by extending long-standing collaborative OA vulnerability research with shellfish growers to include other shellfish users (e.g. port towns, Native American tribes and shellfish sector employees). The project includes five objectives: 1) Map variations in shellfisheries’ exposure to OA and identify those that are most sensitive, 2) quantify production losses from OA and costs of investment in adaptation 3) Identify potential pathways for adaptation, 4) identify key technological, institutional, legislative, financial and cultural barriers to OA adaptation, 5) evaluate the cost of potential adaptation strategies, and develop behavioral models to predict the likelihood of users adopting specific adaptation strategies. The research is designed to identify key vulnerabilities, determine the cost of OA to Pacific Northwest shellfish stakeholders, and to model adaptation pathways for maximizing resilience to OA. The adaptation framework developed here will be replicable in other shellfisheries yet to experience OA impacts.