The Coalition for Science After School (CSAS) was established in 2004 in response to the growing need for more STEM (science, technology, engineering, and mathematics) learning opportunities in out-of-school time. CSAS sought to build this field by uniting STEM education goals with out-of-school time opportunities and a focus on youth development. Over a decade of work, CSAS Steering Committee members, staff and partners advocated for STEM in out-of-school-time settings, convened leaders, and created resources to support this work. CSAS leadership decided to conclude CSAS operations in 2014, as the STEM in out-of-school time movement had experienced tremendous growth of programming and attention to science-related out-of-school time opportunities on a national level. In its ten-year strategic plan, CSAS took as its vision the full integration of the STEM education and out-of-school time communities to ensure that quality out-of-school time STEM opportunities became prevalent and available to learners nationwide. Key CSAS activities included: (1) Setting and advancing a collective agenda by working with members to identify gaps in the field, organizing others to create solutions that meet the needs, identifying policy needs in the field and supporting advocates to advance them; (2) Developing and linking committed communities by providing opportunities for focused networking and learning through conferences, webinars, and other outreach activities; and (3) Identifying, collecting, capturing, and sharing information and available research and resources in the field. The leadership of the Coalition for Science After School is deeply grateful to the funders, partners, supporters, and constituents that worked together to advance STEM in out-of-school time during the last decade, and that make up today's rich and varied STEM in out-of-school time landscape. We have much to be proud of, but as a movement there is much more work to be done. As this work continues to expand and deepen, it is appropriate for the Coalition for Science After School to step down as the many other organizations that have emerged over the last decade take on leadership for the critical work that remains to be done. A timeline and summary of CSAS activities, products, and accomplishments is available for download on this page. All resources noted in the narrative are also available for download below.