Abstract In this paper, state electricity portfolio standards in the U.S. are analyzed to examine how energy efficiency is being created as a particular kind of resource through this type of climate change governance. Such policies can incentivize energy efficiency by requiring or encouraging electricity providers to meet a certain percentage of their demand through energy efficiency measures. North Carolina’s portfolio standard is used as an in-depth case study to identify factors that are then compared across all 36 states that include energy efficiency as part of a portfolio requirement or goal. The main finding of this study is that state portfolio standards tend to emphasize demand-side energy efficiency, or energy efficiency on the customer’s side of the electricity meter, and only rarely incentivize a full range of both demand-side and supply-side efficiency changes. As a result, the amount of energy efficiency and climate change mitigation benefits that are likely to result from this type of portfolio standard policy tool are limited. From this analysis, lessons are drawn out for crafting stronger portfolio standards that incentivize a wider range of efficiency changes across electricity networks.