An ecosystem rehabilitation project in the subhumid 7th Region of central Chile is described, with a three-tiered research and development (R & D) approach that addresses the structure and functioning of soils and vegetation and aims, in the long-term, at a fullscale transformation of the region into a mosaic of agroforestry systems and nature ecosystem reserves. The important role of native and carefully-screened exotic nitrogen-fixing legumes in ''jumpstarting'' the rehabilitation process is underlined. We then suggest that a similar R gr D approach could be applied in the arid ''Norte Chico'' region of northern Chile as well. Apart from immediate interventions, emphasis is placed on revised management of land and water, flora! and fauna through the replacement of ''artificial negative selection'' by a strategy of ''positive selection''. Also noted are the numerous gaps in current knowledge and the grinding socio-economic realities that hinder any rapid realization of our optimistic scenario.