Civic science (CS) is an approach to science learning and action in which youth determine issues of concern in their communities and use science, technology, engineering, and math (STEM) knowledge and methods to address them. In this article, we focus on CS as it is applied to environmental concerns and enacted by children and youth in urban communities. Core CS practices include relevance of local place and culturally responsive principles for youth's learning and community contributions, egalitarian intergenerational partnerships with adults from community-based organizations, teamwork and collective action, and public regard for youth's community environmental contributions. We discuss CS's potential to address the marginalization of youth from minoritized backgrounds in traditional STEM and environmental education. We also argue that the way CS frames science for the public good will prepare younger generations to meet 21st-century environmental challenges.