The acknowledgment of the importance of floodplain forests and their vulnerability to human impacts has raised them as an increasing focus of interest by the environmental legislation in Europe and across the globe. As a result, huge amounts of money are being invested worldwide in their restoration. However, very few studies have reviewed the success or failure of those efforts, which raises alarming uncertainties about their effectiveness and seriously jeopardizes the fulfillment of legislation objectives. The aim of this project is to develop tools to evaluate the success of past floodplain forest restoration projects according to ecologically-based quantitative criteria, with the ultimate purpose of giving experience-based prescriptions to land managers to optimize the resources devoted to the implementation of the current environmental legislation. To achieve this goal, a multi-scale field observation approach is proposed. Data on environmental, management and vegetation variables will be recorded in a series of restored, degraded and reference sites distributed across 2 semi-arid eco-regions of Western US and Southern Europe, with paired climatic gradients that cover different reaches of 6 large river basins (Middle Rio Grande, Arkansas, Upper Colorado, Tagus, Ebro and Garonne). For these sites, the capacity of abiotic variables as success predictors will be assessed on the base of different criteria representing ecological functionality, using cutting-edge multivariate statistical techniques. Leading scientists in the field of riparian restoration ecology will supervise the project in Europe and the US, within the context of well established research institutions well-suited to support the work. Given Dr. Eduardo González’s strong background and history of success, there is no doubt that with IOF fellowship support, the proposed project will greatly enrich his career, positioning him to make substantial contributions to environmental sustainability in Europe.