Agroforestry can help in the battle to control global warming by sequestering atmospheric CO2. Most attention so far has been on the carbon sequestered in trees, but soils can also contain considerable amounts of carbon, some of which is released upon harvest. There has been little quantification of the impact of different land-uses on soil carbon levels due to the high costs and lengthy time periods required to accurately measure soil carbon fluctuations, within and across sites, and over an entire project lifespan. This study attempts to quantify soil carbon changes under agroforestry systems using a modeling approach. The net effects on carbon storage of implementing agroforestry depend on the carbon content of the land-use practices that are replaced. Also, agroforestry projects will impact upon soil carbon levels by preventing land clearing and by maintaining carbon already in the soils. These issues are evaluated from the standpoint of individual landholders, and implications for management of agroforestry systems are discussed.