Pursuant to a congressional request, GAO examined the U.S. Postal Service's oversight of the National Change of Address (NCOA) program, focusing on: (1) how the Postal Service collects, disseminates, and uses NCOA data; and (2) whether the Postal Service adequately oversees the release of NCOA data in accordance with privacy laws. GAO found that: (1) the Postal Service uses 24 licensees to collect and disseminate address-correction information; (2) the licensees provide address services to other private firms and organizations in accordance with standard licensing agreements; (3) the Postal Service has been unable to prevent, detect, or correct potential breaches in the licensing agreement; (4) the Postal Service audits the software that licensees use to match their mailing lists with NCOA files, reviews NCOA advertisements that licensees propose to use, and investigates complaints concerning the NCOA program; (5) Postal Service officials believe that the NCOA licensing agreement helps to ensure that federal privacy guarantees are not compromised through the operation of the NCOA program; (6) the Postal Service has not expressed a clear and consistent position regarding the use of NCOA data to create new-movers lists; (7) the Postal Service failed to terminate the license of any licensee that failed successive process audits in 1992; (8) the NCOA program office is not terminating licensees that fail to maintain address-matching software or enforcing the performance standards prescribed in the license agreements; and (9) the Postal Service needs to enforce these limitations to ensure that the use of NCOA-derived data is limited to the purpose for which it was intended.