Plant maintenance gains greater weight in capital intensive, producing corporations as profit is strongly dependent on optimal use of the plant assets. However, surveys show large saving potentials which can be tapped by a holistic maintenance management system. Furthermore a national study illustrates that the coordinating tools within a maintenance management are weakly distinct and the importance of plant asset management is altogether underestimated. First in this thesis the influence of maintenance on the strategic success factors will be discussed as well as already existing approaches in literature and operational experience for increasing the efficiency and effectiveness in maintenance management. Sequentially management approaches are explained which put a holistic maintenance management in a generic frame. Consecutively the arrangement of an integrated maintenance management model will be focused. To meet the object of this thesis, even the development of a generic assessment model for the maintenance management, it will be discussed about the requirements such a model has to satisfy. Following, approaches from literature and operational experience will be critically appreciated according to their completeness, practicability and quality of reproduction. The needs regarding to the generic completeness and methodology are put into a holistic assessment model. This consists of a content frame and a methodic procedure. The content frame is a combined structure-process model and implies all aspects of a holistic maintenance management system including the business environment. Assessing these aspects according to a maturity model does not end in itself, rather the assessment should initiate a process of discussion about the strengths and weaknesses of the maintenance management and therefore target at the room of improvement. The predefinition and valuation of the results (outcome and impact indicators) enable a strategic controlling process which leads to a suitable development of the maintenance management. The implementation and the partial verification of the model take place in an Austrian company in the primary industry.