Editors' Summary: The Clean Air Act's (CAA's) Title V operating permit program was one of the most significant additions of the 1990 Clean Air Act Amendments. The U.S. Environmental Protection Agency's (EPA's) July 1992 final rules for the Title V program, which are the heart of CAA permitting, set forth the minimum requirements for federally mandated state permit programs. The state operating permit programs will transform the CAA's implementation scheme that has developed since the passage of the CAA in 1970, and change the means by which industry conforms to air pollution control requirements. This Article describes the CAA's Title V operating permit program and EPA's complex final rules for the program. The author details the permitting process and the important differences between EPA's July 1992 final rules and the Agency's May 1991 proposed rules. In doing so, the author examines the rules' distribution of authority between federal and state levels for implementation of the permit program. He concludes that the most important permit program developments will occur at the state level.