This data set contains three ASCII files (.txt format). One file provides net primary productivity (NPP) data for the moist lowland tropical forest on Barro Colorado Island, Panama. NPP estimates are based on field measurements of litterfall accumulation, tree growth and mortality, and herbivory. Above-ground biomass and LAI are also reported. The other two files provide climate data recorded onsite.Annual litterfall accumulation (leaf + twig + other litterfall) averaged 1,064 g/m2/year, excluding losses to herbivory, on the central plateau of the island and in the Lutz catchment (1969-1979) and 1,246 g/m2/year at Poacher's Peninsula (1986-1990). Herbivory due to insects (about 50 g/m2/year) was estimated from leaf litterfall (1974-1977) by measuring holes and gaps in fallen leaves. An additional 30 g/m2/year may be lost to vertebrate herbivores which leave no identifiable traces in litter traps. Coarse wood litterfall due to tree damage may represent an additional 46 g/m2/year. Above-ground biomass averaged 27,425 g/m2 based on inventory data collected every 5 years from 1985 to 2000 and allometric regression equations. Tree growth of 554 g/m2/year was based on above-ground biomass changes during the three census intervals. Tree mortality of 2-3% was estimated by recording dead or missing trees (1982-1990). LAI of 7.3 was based on the average area of leaves that fell per area of ground per year. Overall, above-ground NPP for Barro Colorado Island was estimated at 1,800 g/m2/year.