The existential threat posed by climate change presents a challenge to all those concerned about the next generation. This Element reviews and discusses its implications for the development of children (ages 0-12) today and in the future, and for the parents, teachers, researchers, and professionals who have responsibility for children. This Element adopts a bioecological model to examine both the direct impacts on children's physical and psychological well-being as well as indirect impacts through all the systems external to the child, emphasizing the greater vulnerability of children in the Global South. Given evidence of well-founded climate anxiety, this Element examines children's coping strategies and discusses the key roles of caregivers and schools in protecting and preparing children to face current and future challenges – with knowledge, hope, and agency as central themes. This Element highlights many under-researched areas and calls for action by all those caring for and about children's future.