Abstract: Since 2004, the DETER Cybersecurity Testbed Project has worked to create the necessary infrastructure – facilities, tools, and processes – to provide a national resource for experimentation in cyber security. The next generation of DETER envisions several conceptual advances in testbed design and experimental research methodology, targeting improved experimental validity, enhanced usability, and increased size, complexity, and diversity of experiments. This paper outlines the DETER project's status and R&D directions. For more information, visit: http://www.deter-project.org