This dataset encompasses seagrass information from a long-term Caribbean-wide seagrass monitoring initiative: the Caribbean Coastal Marine Productivity (CARICOMP) program. Seagrass monitoring was conducted at 22 sites with 52 sampling stations from 1993 until 2012, although many concluded the monitoring program before 2007. There were one to six sampling stations per site. Leaf productivity monitoring included marking Thalassia testudinum leaves within quadrats (20 x 10 cm) in four to six replicates at each station. Seagrass leaves remained growing in the field and were sampled approximately one week later. Samples were processed in the laboratory to quantify old standing biomass and new growth since the date of marking. Foliar shoots were counted within quadrats and density estimated. Sampling replication, frequency, and dates varied among sites. The dataset includes 5900 entries.