After-school programs are a source of powerful, positive experiences for an estimated eight to ten million youth, especially those in low-income, under-represented populations (the majority of youth in these programs). Through this conference grant, TERC, along with the Exploratorium and the Lawrence Hall of Science, proposes to launch a national initiative to create, support and sustain engaging, research-based science and mathematics activities in the after-school community. This planning conference will bring together the leaders and experts who run exemplary after-school programs, create quality science and mathematics materials, and provide effective staff training to identify the challenges, goals and questions of greatest interest and value to the national community. Intellectual merit and broader impact are evidenced by the gathering of key players, promotion of dialog and the facilitation of connections between developer and after-school communities.