The 1990 Clean Air Act amendments established an operating permit system that is affecting many new and existing sources of air emissions, as well as state and local air pollution control agencies. After delays and early missteps, the operating permit program is moving ahead. All state and local programs have received interim or full approval, and permits are being issued, although at a slower rate than anticipated. However, a number of issues exist. These include the effect of key federal regulations, not yet promulgated, on permit programs and regulated sources; adequacy of state resources; gaining full approval for those permit programs that now have interim approval; and oversight.