This paper was the result of a series of workshops we got funded through the US National Center of Environmental Synthesis and iDiv (Germany). We built the frist large database on ecosystem restoration where we estimated how much we are losing in restored ecosystem compared with ecosystems that were undisturbed. Using a novel mathematical approach we estimated the area between the recovery trajectory curve and the reference constant to estimate the recovery debt, a concept that we coined. We found that restored ecosystem were on average 30% less diverse, hosted 50% less animals and plants, and were 40% less efficient in the cycling of carbon and nitrogen than reference, undisturbed ecosystems. Since we built this database, we have learned of two other initiatives mimicking our effort. Several papers have been published using our mathematical approach to estimate the recovery debt.