In this article, we review local climate action plans and their associated greenhouse gas (GHG) emissions inventories from 30 U.S cities in order to assess the degree to which climate action plans are informed by such inventories and to identify choices and assumptions the inventories require that may influence climate action plan policies and proposed actions. We hope this will help planners preparing climate action plans make informed, clear, and defensible choices, as well as optimize policy development and implementation in their communities. In addition, we hope that this research will contribute to refining future GHG emissions inventory protocols and climate action planning methods.