NGSS Early Implementers is a four-year initiative created to help eight California school districts and two charter management organizations, supported by WestEd's K-12 Alliance, implement the Next Generation Science Standards (NGSS). This evaluation report describes how site and district administrators are making critical contributions to the implementation of the NGSS. Intended for administrators and state education leaders, this report illustrates how: (1) Administrators are advancing NGSS implementation in their schools and districts; (2) Teachers are benefitting from administrators' support; and (3) The Initiative is empowering administrators' efforts. The report also describes how the Initiative is providing substantial professional learning and assistance for administrators and empowering them to advocate and actively support their teachers' NGSS implementation. The report concludes with four recommendations for NGSS implementation at the site and district levels, including: (1) Communicating that science is a priority school subject; (2) Giving teachers flexibility to try the substantially new science instruction of NGSS, including some freedom to integrate science and other school subjects; (3) Increasing both teacher-to-teacher and teacher-with-administrator collaboration around teaching science; and (4) Providing resources for science instruction.