Abstract:The primary purpose of this study is to open up the black box of peer review and to increase its transparency, understanding, and credibility. To this end, two arguments will be presented: First, epistemic and social aspects of peer review procedures are inseparable and mutually constitutive. Second, a content analysis of written reviews indicates that certain elements of peer culture from the 17 th century are still active in the scientific community. These arguments are illustrated by a case study on the peer review practices of a national funding institution, the Swiss National Science Foundation. Based on the case study and the two arguments it will be concluded more generally that peer review procedures show a distinctive specificity to the reviewed objects (e.g. papers or proposals), the organisational format (e.g. panels or external reviewers), or the surrounding context (e.g. disciplinary or interdisciplinary). Scientists, administrators, and the public may conclude that appraising peer review procedures should not be done by way of general principals but should be based on concrete factual knowledge on the specific process under discussion.3