Summary: The Ships Parts Control Center manages the Navy's stock of ship and submarine parts. GAO found weaknesses in the center's internal controls over and monitoring of planned program requirements. Specifically, the center's files contained duplicate and unauthorized planned program requirements, as well as inappropriate requirements for which the center did not budget and did not use to support specific supply actions. In addition, the center's written guidance for validating these requirements was inadequate. Duplicative and unauthorized payments could result in the procurement of unneeded materials. Although the planned program requirement system has been used by the Navy for many years, adequate program management data were unavailable to determine how well it operated. Improved control over and monitoring of the system by the center could help ensure that the Navy's planned program requirements are valid and satisfied promptly and efficiently. The center has taken steps to identify system problems and has reduced the number of planned program requirements in its files. The center also plans to emphasize this subject in its next management control review cycle.