Approved for public release, distribution unlimited / The maintenance of large military software systems is complex, involves users as well as software professionals, and requires appropriate management, which is one of the most important factors in efficient maintenance. Maintenance management requires information about the current state of the maintenance process that should be organized within a maintenance-oriented Enginering Database. This database should include all the necessary data about software changes, system configeration, maintenance task scheduling, etc., and it should be based on a realistic model of the maintenance process. This tesis proposes a mathematical Model of Software Maintenance that uses graphs to model the relationships between maintenance tasks and software components. The Model addresses the dynamic behavior of the maintenance process and supports priority and precedence of maintenance activities. The proposed Model of Software Maintenance provides a sound basis for implementation of a maintenance-oriented engineering database that supports automation of maintenance management, e.g., process control, task scheduling, job assignments, planning and forecast, gathering and interpretation of maintenance statistics and metrics, etc.