"A Framework for K-12 Science Education and Next Generation Science Standards" (NGSS) describe a new vision for science learning and teaching that is catalyzing improvements in science classrooms across the United States. Achieving this new vision will require time, resources, and ongoing commitment from state, district, and school leaders, as well as classroom teachers. Successful implementation of the NGSS will ensure that all K-12 students have high-quality opportunities to learn science. "Guide to Implementing the Next Generation Science Standards" provides guidance to district and school leaders and teachers charged with developing a plan and implementing the NGSS as they change their curriculum, instruction, professional learning, policies, and assessment to align with the new standards. For each of these elements, this report lays out recommendations for action around key issues and cautions about potential pitfalls. Coordinating changes in these aspects of the education system is challenging. As a foundation for that process, "Guide to Implementing the Next Generation Science Standards" identifies some overarching principles that should guide the planning and implementation process. The new standards present a vision of science and engineering learning designed to bring these subjects alive for all students, emphasizing the satisfaction of pursuing compelling questions and the joy of discovery and invention. Achieving this vision in all science classrooms will be a major undertaking and will require changes to many aspects of science education. "Guide to Implementing the Next Generation Science Standards" will be a valuable resource for states, districts, and schools charged with planning and implementing changes, to help them achieve the goal of teaching science for the 21st century. [Contributors include the Division of Behavioral and Social Sciences and Education; Board on Science Education; and Committee on Guidance on Implementing the Next Generation Science Standards.]