Our goal was to establish a global database of seagrass trajectories, i.e. reported, quantitative changes in extent showing decline, increase, or stability over time. We compiled existing quantitative data on seagrass areal extent, density, percent cover, and/or biomass from published studies, reports, websites, online databases, and unpublished sources. These sources were identified by: 1) conducting a Web of Science searh using the following search words: (seagrass* or SAV) and (loss* or change* or recovery or stability or dynamic* orimpact* or map* or decline* or increase* or gain*); this search returned 2346 references, and 2) requesting relevant data on the Seagrass Forum listserve. Studies were included in the analysis if they covered a period greater than two years and included two or more estimates of areal extent for the same site across time. Before analyzing the data, we performed several verification steps to assess accuracy, including a complete, independent check of 16% of the entries (80 sites).