Abstract:This paper addresses the direct and indirect relationships between the National Environmental Policy Act (NEPA) and the new conformity requirements. This paper concludes that NEPA and transportation/air quality conformity processes should be concurrent. The need for concurrent determinations is supported by five arguments: 1) the legislative history of conformity indicates that project conformity determinations be made during the NEPA process; 2) general NEPA requirements specify coordination between environmental processes; 3) the level of technical detail required for conformity analyses meets or exceeds the level already required for NEPA; 4) unless conformity is taken into account, alternatives and mitigation measures generated during the NEPA analytical process may later result in a negative conformity determination; and 5) public comment periods, unless coordinated, would run consecutively rather than concurrently, potentially delaying project implementation.