A model for optimizing the assignment of maintenance actions for a piece of equipment is developed in the thesis. The model considers the detectability and the criticality of component failure in order to assign a maintenance instruction. The thesis also develops the framework for an integrated maintenance management system. The system consists of three modules. The first module is work control. It is used to prepare, schedule, and insure the execution of maintenance instructions. The second module is the equipment condition control module which monitors maintenance effectiveness and accordingly updates the maintenance instructions. The third module is cost control. This is the tool used to monitor the economical performance of the maintenance function. An equipment information system is also presented, and two futuristic maintenance proposals are introduced. The model and the integrated maintenance management system, constitute a strong tool, that equipment managers can use to optimize the maintenance function, and improve the mechanical, operational, and economical performance of equipment. / Master of Science