Seed and seedling data used in "Lifespan of tropical trees from seed to 1-cm diameter", Forest Ecosystems (in press, 2025). Seed data include counts of seeds and germinants at Barro Colorado Island, Panama, as described in detail in the manuscript. The data are in the file BCISeedGermination.csv, a tab-delimited ascii text file. Each row has a count of the number of germinants for one species in one year along with a count of the number of seeds of the same species one year earlier. There are four columns of data: sp: Species, identifed by a six-letter code (manuscript Table 2)year: Year of count of germinantsgerm: Number of germinants countedseedPriorLag: Number seeds counted in prior year (except in species faraoc, which has 2-year lag) Seedling data include measurements of individual seedlings throughout their lifetimes from the Wright seedling censuses at Barro Colorado Island, Panama, as described in detail in the manuscript. The data are in the file BCISeedling.csv, a tab-delimited ascii text file. Each row has a set of measurements for one seedling in one year, with nine columns of data: sp: Species, identifed by a six-letter code (manuscript Table 2)tag: Tag number identifying the individual seedlingyear: Year of measurementstatus: Code describing state of individual, A=alive, D=dead, AN=alive but not measured, M=missed and not measuredage: Age in years since germinated; NA for those in census > 50 cm height (see manuscript)ht: Height in cm to growing tipsizeOrig: Size class based on height and dbh, an integer 1-5 (defined in manuscript Table 1)size: Size as used in analyses, including age (after period), and filled in for missed measurements (see manuscript)dbh: Stem diameter in mm at breast height (1.3 m above ground)