In Japan, environmental education (EE), education for sustainability (EfS) or education for sustainable development (ESD) have long been missed in early childhood education (ECE) academia nor mentioned in ECE guidelines. In this chapter, we particularly discuss the importance of connecting children’s experience to fostering an ecological worldview, a worldview based on ecology as a natural science. We argue a sustainable society cannot be formed based on worldviews where it is acceptable to destroy nature or where economic growth takes precedence, even if children can think critically and be active agents. We believe that ecologically informed participation, based on an ecological worldview, is necessary, not just participation for transforming towards a sustainable society. Here, we examine: (1) whether the current Japanese ECE guidelines contain descriptions that might refer to an ecological worldview in comparison with the national guidelines of Sweden, Korea, and Australia; and, (2) whether the Japanese ECE guidelines contain descriptions with potential for fostering an ecological worldview and promoting ecologically informed participation. Then we share two model cases implemented under the current Japanese ECE guidelines to illustrate some transformative possibilities. Finally, we consider how the ecological lens of educators and the organizational culture of each ECE centre is most influential for implementing EfS.