The second biennial ACEEE City Energy Efficiency Scorecard measures the progress of city policies and programs that save energy while benefiting the environment and promoting economic growth. We ranked 51 large US cities for their energy efficiency efforts across five policy areas: local government operations, community-wide initiatives, buildings, energy and water utilities, and transportation. The Scorecard also gives examples of best practices in each policy area. In this year's results, Boston retained its position at the top of the rankings. Joining Boston in the top five were New York City, Washington DC, San Francisco, and Seattle. The most-improved cities since the last edition were Washington, Los Angeles, Chicago, Minneapolis, and Seattle. Overall, we found that cities are still laboratories of innovation, pushing the envelope to reduce energy waste. The Scorecard offers a roadmap for any local government aiming to improve its energy efficiency by learning from other cities’ successes and customizing strategies to suit its own priorities.