Since 2018, an initiative of the Consultative Group on International Agricultural Research (CGIAR) has been addressing the unprecedented challenges faced by farmers to deal with changing and variable climates and related crop management problems caused by (new) biotic and abiotic stresses. It builds on previous work of Bioversity International and partners in various countries of Africa, Asia and Latin America and aims to combine and scale, from the local to the global level, successful strategies, methods and tools that increase farmers’ and their communities’ timely availability, affordability and improved access to good-quality seed of a portfolio of crops and crop varieties, including novel ones that are better adapted to climate change. Structured seed legislation is important to guarantee the necessary seed quality to farmers. Core components are: (1) building resilient seed systems, including through seed system characterization, introducing promising crop diversity for climate change, strengthening community seed banks and enterprise development; (2) supportive policies and laws; and (3) national, sub-regional and global networking. Central to the scaling strategy is engagement with the private seed sector and local and national governmental and non-governmental organizations that are well positioned to take up and further develop the tested strategies, methods and tools.