Scientific consensus is that the recently observed increase in levels of atmospheric carbon dioxide is caused primarily by burning of fossil fuels, industrial processes and deforestation. However, the rate of this increase has been much slower than would be expected from a simple tally of known carbon sources and sinks, suggesting that carbon is ?missing? from the existing carbon budget. New research indicates that tropical forests are absorbing significantly more carbon than previously thought, a finding that could help account for the missing carbon. A critical question remains: how much carbon sequestration is carried out by mature versus by regenerating forests? This work begins to answer this question by improving our understanding of the role that regenerating forests play in the carbon budget of tropical forests. The author presents an operational methodology for mapping carbon pools of tropical regenerating forests at regional scales. Integrating site-level forest inventory measurements with satellite imagery in the Amazon and the Congo Basin, the author presents wall-to-wall maps of carbon pools at different stages of forest regeneration in both regions.