Information technology (IT) has to face many challenges regarding the increasing business requirements for flexibility, complexity, and availability of IT. Thus, a restructuring of the IT portfolio into IT services is necessary to provide an effective and business-driven IT support. The design of IT service catalogues is generally difficult in the managerial context of an enterprise. The current situation of the IT service structure can hardly be analyzed because no approaches exist that support such an analysis. In this paper we intend to develop a maturity model to assess the current situation of the quality of IT service catalogues. We describe the model structure, its components, and present empirical key findings of its practical application in a benchmarking study.