Abstract: Global climate change brings up fundamental questions related to intragenerational and intergenerational equity. Economists have traditionally drawn a sharp distinction between efficiency and equity, but more recent studies in ecological economics have argued that the two are intimately linked (Corbera, Brown, & Adger, 2007; Howarth & Norgaard, 1992; Muradian, Corbera, Pascual, Kosoy, & May, 2010; Pascual, Muradian, Rodríguez, & Duraiappah, 2010). This paper investigates the relationship between economic efficiency and equity within a central tool used for climate change policies: Integrated Assessment Models. Because efficiency is a fundamental concept and goal for economics, understanding this relationship is important to understanding the role that economics can, and cannot, play in the transition to a more sustainable society.