Published almost at the halfway point of the 2011–2020 Strategic Plan for Biodiversity, this fourth edition of the Global Biodiversity Outlook (GBO-4) provides a timely report: on progress towards meeting the 20 Aichi Biodiversity Targets and potential actions to accelerate that progress; on prospects for achieving the 2050 Vision on ‘Living in Harmony with Nature’; and on the importance of biodiversity in meeting broader goals for sustainable human development during this century.