The Green Libraries Partnership, rebranded as the Green Libraries Campaign in 2023, was established in February 2022 in response to the UN Climate Change Conference and the climate emergency declarations by local authorities in England. The initiative, led by the Chartered Institute of Library and Information Professionals (CILIP) and supported by key organisations, aims to foster a sustainable future for libraries and their communities. Central to its mission are four key aims: enhancing sustainability efforts within libraries, facilitating community engagement, aligning with local environmental initiatives, and positioning libraries as vital contributors to climate action. Over its first eighteen months, the Partnership conducted research, launched a Green Libraries Manifesto, established a grant fund, and hosted the inaugural Green Libraries Conference, reflecting its commitment to environmental action. The Green Libraries Campaign seeks to expand the programme’s reach across the UK library sector, encouraging collaboration and innovation to address climate change effectively. This article outlines the objectives of the Partnership and Campaign, evaluates achievements thus far, and discusses future aspirations, emphasising the importance of libraries in promoting climate awareness and action. As the initiative evolves, it aspires to ensure financial sustainability while fostering an inclusive network of libraries dedicated to environmental stewardship. The programme is also committed to learning from global library initiatives to support diverse communities in their sustainability efforts and the measures being taken across the international library sector to work towards achieving new zero across library buildings and services.