This mixed-methods study examined how ten- to twelve-year-old children experienced and made sense of their growing climate change awareness through an after-school program that used participatory methods to facilitate children's informed climate change action. The fifteen-week program combined hands-on educational activities with digital photography and culminated in youth-led action projects focused on individual (i.e. daily habits) and collaborative change (i.e. community projects). After the program, children knew significantly more about the scientific and social dimensions of climate change than before, and more than the average U.S. teen or adult. Survey and focus group analyses showed that, in addition to learning, children were inspired and motivated by their growing climate change awareness. Children felt empowered by their knowledge and eager to learn more and take action to minimize harms. Towards theorizing children's constructive climate change engagement, the importance of informal learning environments for children's intergenerational and political influence is discussed.