The National Aeronautics and Space Administration (NASA) is one of the United States' leading federal science, technology, engineering, and mathematics (STEM) agencies and plays an important role in the landscape of STEM education. In 2015, NASA's Science Mission Directorate (SMD) created the Science Activation (SciAct) program to increase the overall coherence of SMD's education efforts, to support more effective, sustainable, and efficient use of SMD science discoveries for education, and to enable NASA scientists and engineers to engage more effectively and efficiently in the STEM learning environment with learners of all ages. SciAct is now transitioning into its second round of funding, and it is beneficial to review the program's portfolio and identify opportunities for improvement. "NASA's Science Activation Program: Achievements and Opportunities" assesses SciAct's efforts towards meeting its goals. The key objectives of SciAct are to enable STEM education, improve U.S. scientific literacy, advance national education goals, and leverage efforts through partnerships. This report describes and assesses the history, current status, and vision of the program and its projects. It also provides recommendations to enhance NASA's efforts through the SciAct program. [Contributors include Committee to Assess Science Activation; Board on Science Education; and Division of Behavioral and Social Sciences and Education.]