California is considering the adoption of a cap-and-trade regulatory mechanism for regulating the greenhouse gas emissions from electricity and perhaps other industries. Two options have been widely discussed for implementing cap-and-trade in the electricity industry. The first is to regulate the emissions from electricity at the load-serving entity (LSE) level. The second option for implementation of cap-and-trade has been called the “first-seller” approach. Conceptually, under first-seller, individual sources (i.e. power plants) within California would be responsible for their emissions, as with traditional cap-and-trade systems. Emissions from imports would be assigned to the “importing firm.” An option that has not been as widely discussed is to implement a pure source-based system within California, effectively excluding imports from the cap-and-trade system altogether. This paper examines these three approaches to implementing cap-and-trade for California’s electricity sector. The paper surveys many of the issues relating to measurement and the impacts on bidding and scheduling incentives that are created by the various regulatory regimes.