In 2007, Hawaii became the second State after California to adopt binding greenhouse gas reductions targets in ACT 234. The legislation follows the example set by California in attaining 1990 levels of greenhouse gas emissions by the year 2020. The State of Hawaii Department of Health Clean Air Branch is tasked to regulated emissions through the use of market-based mechanisms – essentially building a market for greenhouse gas pollution. While ACT 234 was in many ways modeled after California’s AB32, it is also recognized that Hawaii has unique economic and environmental characteristics. Hawaii will require policies tailored to its island features. This brieﬁng provides a primer on greenhouse gas regulation options and how they might be applied to the case of Hawaii.