Based on the outcomes of international studies, which show the inadequateness of the German education system, fostering learners' competencies becomes increasingly relevant. In order to further improve the quality of the German education system, educational policy requires the education system to implement national educational standards. These standards delineate how learning and teaching in schools should take place. Teaching and learning should be based on empirically-grounded competence models that should be developed by domain experts and psychologists cooperatively. For the evaluation of these competence models, educational policy demands the development of appropriate instruments to measure relevant competencies as well. In order to fulfill these demands, the development of an empirically-grounded competence model and a respective instrument will be described for the domain of computer science modeling. First, the relevance of object-oriented modeling for computer science education will be shown. Hereafter, the development of an empirically-grounded competence model and an associated test instrument will be shown.The development of the competence model requires two intermediate steps: In the first step it will be shown how the dimensions and components of the model can be derived theoretically. In a second step, the competence model will be refined empirically by referring to the results of the qualitative content analysis of experts interviews conducted in 2009 and 2010. In the interviews, three groups of experts have been interviewed: (1) experts of computer science, (2) experts of computer science education and (3) expert computer science teachers.Based on the empirically-grounded competence model, the development of an instrument for measuring competencies will be described. Here, the creation of items to prove the respective competencies covered in the competence model will be illustrated.