Dissolved organic carbon (DOC) is a key component of the ocean’s carbon system. DOC plays an important role in the cycling of organic matter and the functioning of marine ecosystems. It is essential that DOC measurements be accurate and comparable across labs to understand how carbon is produced, transformed, and transported through the ocean. The consensus reference material (CRM) program has provided the international research community with calibration standards since 1998. These materials improve the reliability of DOC data across laboratories and regions. This project will support the DOC CRM Program for three more years. The Program will produce and distribute reference waters collected from surface, mid-depth, and deep layers of the Florida Strait to over 300 laboratories in more than 50 countries. These reference materials provide consistency to the measurements that contribute to global DOC datasets being used to examine spatial and temporal variability in the ocean. To further build analytical capacity across the community, the project also distributes DOC-TN Determination Kits. These kits include all necessary calibration and reference materials, along with guidelines for measuring DOC and total nitrogen (TN). These efforts enable high-quality data collection, support open and reproducible science, and promote the advancement of ocean observation on a global scale. The project also provides training for the next generation of DOC analysts. The project involves t