Coastal, estuarine, and marine ecosystems play a substantial role in carbon sequestration and storage ("blue" carbon), as documented by international reports. In particular, coastal habitats such as salt marsh, mangrove forests, and seagrass beds are net carbon sinks storing up to three to five times more carbon than tropical forests by area. Thus, these ecosystems play an important role in climate mitigation and adaptation. Protection and restoration of these coastal ecosystems provide these climate-related benefits, while also supporting a variety of critical ecosystem services. As a result, there is growing interest domestically and internationally in better understanding the carbon storage and sequestration functions of these coastal habitats and developing carbon market protocols for valuing these carbon services. The ultimate goal of these efforts is to develop incentives, including greenhouse gas accounting protocols, that will prevent degradation of these valuable habitats and subsequent rapid release of their large carbon stores that contribute to global climate change. To achieve these goals, innovations in natural and social science as well as policy are needed. The objectives of this symposium are to share recent advances in both the science and policy of coastal carbon and connect those advances to decision-making in the United States and internationally.