The EPA proposes to revise its General Conformity regulations implementing the Clean Air Act (CAA) requirement that emissions caused by general federal activities that occur within nonattainment and maintenance areas must conform to the purpose of a state, federal, or Tribal implementation plan. This action is proposed to fulfill the CAA directive to periodically update and revise the implementing regulations and keep the EPA Administrator informed about general federal activities and their impact on the National Ambient Air Quality Standards (NAAQS). This action proposes updates to the regulations that will reflect the latest scientific and environmental practices and policies affecting the use and interpretation of the program that occurred in the time since the last major update in 2010. The EPA is not proposing to make substantive changes to any General Conformity program requirements. Instead, this action proposes to add clarifications and correct errors to increase stakeholders’ understanding of the requirements, promote consistency of conformity evaluations prepared across the federal agencies, and make the conformity process more efficient by removing redundancy.