Efforts to put a price on greenhouse gas emissions are increasing, with approaches including carbon taxes and cap-and-trade programs currently in effect in 15 states and provinces plus one city. Several other states and provinces are also considering putting a price on emissions. This paper describes these efforts and analyzes their impact, including their implications for energy efficiency. Evaluations of long-term programs find that they reduce energy use and greenhouse gas emissions without a serious impact on local economies. The effect of a carbon price on consumers and the broader economy can be cushioned when some of the funds generated are invested in energy efficiency and energy consumption is lowered. [Webinar Slides]