Calculating greenhouse gas emissions reductions from climate change mitigation projects requires construction of a baseline that sets emissions levels that would have occurred without the project. This paper describes a standardized multiproject methodology for setting baselines, represented by the emissions rate (kg C/kWh), for electric power projects. A standardized methodology would reduce the transaction costs of projects. The most challenging aspect of setting multiproject emissions rates is determining the vintage and types of plants to include in the baseline and the stringency of the emissions rates to be considered, in order to balance the desire to encourage no- or low-carbon projects while maintaining environmental integrity. The criteria for selecting power plants to include in the baseline depend on characteristics of both the project and the electricity grid it serves. Two case studies illustrate the application of these concepts to the electric power grids in eastern Ind ia and South Africa. We use hypothetical, but realistic, climate change projects in each country to illustrate the use of the multiproject methodology, and note the further research required to fully understand the implications of the various choices in constructing and using these baselines.