To become robust scientific thinkers, children need meaningful opportunities to engage in science learning across a variety of contexts. Unfortunately, many children, especially those in urban settings and from low-income families, do not get the experiences needed to deepen their understanding of a broad range of scientific ideas, nor do they have consistent opportunities to engage in the practice of science. Informal and outdoor education programs offer a pathway to provide meaningful science learning experiences that prepare children for school and beyond, as well as offer health benefits of being physically active and outdoors. This paper discusses a federally funded initiative to develop a Toolkit and to research its promise for supporting children's active, outdoor environmental science learning through the use of digital resources and hands-on activities. Findings showed that the Toolkit positively influenced participants' behaviors and supported educators and parents in engaging children with focal science concepts and practices across a range of informal, outdoor contexts (e.g., local park departments, nature centers, school-based after-school programs with open green space).