Restoration of degraded drylands is urgently needed to mitigate climate change, reverse desertification and secure livelihoods for the two billion people who live in these areas. Bold global targets have been set for dryland restoration to restore millions of hectares of degraded land. These targets have been questioned as overly ambitious, but without a global evaluation of successes and failures it is impossible to gauge feasibility. Here we examine restoration seeding outcomes across 174 sites on six continents, encompassing 594,065 observations of 671 plant species. Our findings suggest reasons for optimism. Seeding had a positive impact on species presence: in almost a third of all treatments, 100% of species seeded were growing at first monitoring. However, dryland restoration is risky: 17% of projects failed, with no establishment of any seeded species, and consistent declines were found in seeded species as projects matured. Across projects, higher seeding rates and larger seed sizes resulted in a greater probability of recruitment, with further influences on species success including site aridity, taxonomic identity and species life form. Our findings suggest that investigations examining these predictive factors will yield more effective andinformed restoration decision-making.Fil: Shackelford, Nancy. University of Victoria; Canadá. State University of Colorado at Boulder; Estados UnidosFil: Paterno, Gustavo B.. Universidade Federal do Rio Grande do Norte; Brasil. Universitat Technical Zu Munich; AlemaniaFil: Winkler, Daniel E.. Southwest Biological Science Center; Estados UnidosFil: Erickson, Todd E.. University of Western Australia; Australia. Kings Park; AustraliaFil: Leger, Elizabeth A.. University of Nevada; Estados UnidosFil: Svejcar, Lauren N.. Eastern Oregon Agricultural Research Center; Estados UnidosFil: Breed, Martin F.. Flinders University. College Of Science And Engineering.; AustraliaFil: Faist, Akasha M.. New Mexico State University.; Estados UnidosFil: Harrison, Peter A.. University of Tasmania; AustraliaFil: Curran, Michael F.. University of Wyoming; Estados UnidosFil: Guo, Qinfeng. Southern Research Station; Estados UnidosFil: Kirmer, Anita. Anhalt University of Applied Sciences; AlemaniaFil: Law, Darin J.. University of Arizona; Estados UnidosFil: Mganga, Kevin Z.. South Eastern Kenya University; KeniaFil: Munson, Seth M.. US Geological Survey; Estados UnidosFil: Porensky, Lauren. Agricultural Research Service Rangeland Resources and Systems Research Unit; Estados UnidosFil: Quiroga, Raul Emiliano. Universidad Nacional de Catamarca. Facultad de Ciencias Agrarias. Departamento de Sanidad Vegetal.; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Catamarca-La Rioja. Estación Experimental Agropecuaria Catamarca; ArgentinaFil: Török, Péter. MTA-DE Lendület Functional and Restoration Ecology Research Group; HungríaFil: Wainwright, Claire E.. Tennessee Department of Environment and Conservation; Estados UnidosFil: Abdullahi, Ali. Hirola Conservation Programme; KeniaFil: Bahm, Matt A.. USDA Natural Resources Conservation Service; Estados UnidosFil: Ballenger, Elizabeth A.. National Park Service; Estados UnidosFil: Barger, Nichole. State University of Colorado at Boulder; Estados UnidosFil: Baughman, Owen W.. The Nature Conservancy of Oregon; Estados UnidosFil: Becker, Carina. University of Cape Town; SudáfricaFil: Lucas Borja, Manuel Esteban. Universidad de Castilla-La Mancha; EspañaFil: Boyd, Chad S.. USDA Agricultural Research Service; Estados UnidosFil: Burton, Carla M.. University of Northern British Columbia; CanadáFil: Burton, Philip J.. University of Northern British Columbia; CanadáFil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Sur. Estación Experimental Agropecuaria Santa Cruz; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santa Cruz. Universidad Tecnológica Nacional. Facultad Regional Santa Cruz. Centro de Investigaciones y Transferencia de Santa Cruz. Universidad Nacional de la Patagonia Austral. Centro de Investigaciones y Transferencia de Santa Cruz; Argentin