The BIO-JUST  project investigates the implications of environmental justice in the design, implementation, and evaluation of Nature-Based Solutions (NbS) for watershed provisioning of ecosystem services in seven different case studies in Europe (Spain, France, The Netherlands and Portugal) and Latin America (Brazil, Colombia and Ecuador). It brings together perspectives from environmental justice, political ecology, environmental anthropology, critical institutional analysis and ecological economics in a multidisciplinary approach to question which types of NbS, under which conditions, generate or reinforce inequalities and conflicts, and which promote socially just outcomes while simultaneously promoting biodiversity conservation and water security. The novelty of the project lies in the qualitative, quantitative, integrated and participatory evaluation of the implications of environmental justice and the conservation impacts of various NbS for ecosystem services in areas that are biodiversity hotspots, pioneering countries in NbS implementation, or located in particularly water-scarce areas, but which diverge in terms of institutional configuration, management entity, age, size, biophysical context, and therefore offer the necessary variety to deliver robust comparative results.