To use public funds effectively, the government must employ effective management practices and processes, including the measurement of government program performance. In addition, legislators, government officials, and the public want to know whether government programs are achieving their goals and what their program costs are. The U.S. Government Accountability Office (GAO) has shown that in order to conduct oversight of the federal government, including agencies’ stewardship of public funds, reliable cost information is required. We originally developed this guide in order to establish a consistent methodology based on best practices that can be used across the federal government for developing, managing, and evaluating program cost estimates. The Cost Estimating and Assessment Guide presents the best practices associated with developing a reliable, high-quality cost estimate and the best practices associated with effective management of program cost through the use of earned value management (EVM). Use of these best practices should enable government programs to better estimate and manage their costs to improve program management and execution.