The EPA is taking final action to grant full approval of the State of Maryland's operating permit program. Maryland's operating permit program was submitted in response to the Clean Air Act Amendments of 1990 that required each state to develop, and submit to EPA, a program for issuing operating permits to all major stationary sources and to certain other sources within the state's jurisdiction. The EPA granted final interim approval of Maryland's operating permit program on July 3, 1996. The State of Maryland amended its operating permit program to address the deficiencies identified in the final interim approval action, and this final rulemaking action approves those amendments. The EPA proposed full approval of Maryland's operating permit program in the Federal Register on September 10, 2002. This final rulemaking summarizes the comments EPA received on the September 10, 2002 proposal, provides EPA's responses, and promulgates final full approval of the State of Maryland's operating permit program.