This is the first in a series of papers intended to guide states as they embark on the path to Clean Power Plan compliance. This guide highlights steps states can take to use energy efficiency as a key compliance strategy. We help states identify critical decisions and their implications for energy efficiency, and we describe opportunities for identifying and engaging important stakeholders. We also provide guidance for evaluating energy efficiency compliance options, including strategies and tools for comparing options, measuring and verifying energy and emission savings, and incentivizing energy efficiency.