In 2005, the National Research Council report Rising Above the Gathering Storm recommended a new way for the federal government to spur technological breakthroughs in the energy sector. It recommended the creation of a new agency, the Advanced Research Projects Agency-Energy, or ARPA-E, as an adaptation of the Defense Advanced Research Projects Agency (DARPA) modelwidely considered a successful experiment that has funded out-of-the-box, transformative research and engineering that made possible the Internet, GPS, and stealth aircraft. This new agency was envisioned as a means of tackling the nation’s energy challenges in a way that could translate basic research into technological breakthroughs while also addressing economic, environmental, and security issues. Congress authorized ARPA-E in the 2007 America COMPETES Act and requested an early assessment following 6 years of operation to examine the agency’s progress toward achieving its statutory mission and goals. This report documents the results of that assessment. It includes both an operational assessment of the agency’s funding programs and a technical assessment of its awards, to the extent possible.