The article reports on a case study of impact evaluation of internal quality assurance, i.e. Programme Reviews, which was carried out by the Evaluation Agency Baden-Wuerttemberg and the Staff Unit of Quality Development at University of Stuttgart (Germany) in the form of a methodological before-after comparison. The impact evaluation exhibits that the external evaluations of Programme Reviews were in tune with the idea of a 'critical friend' approach, stressing the positive aspects while including some constructive criticism. It is shown that the evaluations initiated intended constructive discussions about the programmes, while the integration of internal and external evaluations in the Programme Review needs to be improved. A further related result is that programmes need more extensive feedback to improve acceptance from critical corners. Finally, a series of open answers gives indications for possible improvement of the university's quality assurance and organizational structures, including a better and fair integration of students in quality assurance and a more strategic orientation/integration of teaching and learning.