Many species-rich tropical rain forests are characterized by high biomass and productivity. It remains unclear how this productivity is partitioned within the forest. Here, we examine the relationship between biomass and productivity among tree species and locations in the Pasoh 50-ha plot in Malaysia. We find negative correlations between biomass and specific productivity, best approximated by a power functions with scaling exponents of approximately –0.12 for across species and approximately –0.6 across locations. These correlations arise from the decline in relative growth rate as a tree grows due to the increased proportion of wood versus energy-capturing leaves, thereby adult trees in large-statured (“taller”), high-biomass populations show lower specific productivity than those in short-statured (“shorter”) low-biomass populations. Contrary to specific productivity, total biomass productivity relative to leaf biomass is larger for taller populations, reflecting high net assimilation rates by full-lit canopy trees. Our results contradict the commonly-reported tendency that taller species grow better than shorter species at all reference sizes. We show that the marked growth decline of tall species at large adult sizes offset the effect of high growth rate at small sizes on population productivity.