Open Science (OS) has emerged as a normative ideal in research, yet the institutional uptake is highly uneven. Nosek [1] places policy at the top of his pyramid for achieving cultural change toward OS, characterizing it with the imperative to “make it required”. However, the impact of policies lies in the detail of the actual translation of OS practices. Developing institutional policies and determining concrete commitments and measures is a complex endeavour, framed by disciplinary contexts and their underlying practices. In the project IvOS, we raise the question: Do Open Science policies truly drive cultural transformation in research, or do they serve primarily symbolic functions under the guise of compliance? This study addresses this tension by empirically investigating the content and perceived impact of institutional OS policies within a highly interdisciplinary and heterogeneous research network. The database consists of OS policy documents (n = 79) of Leibniz Institutions. These are coded applying qualitative content analysis (results of a pre-study are available [2]). The analysis focus lies on the OS dimensions (Open Access, Open Data, OER, etc.) [3], the practices addressed and their binding character [4], the consideration of discipline-specific concepts and inclusion [5], the implementation into institutional strategies and good scientific practice [6] as well as the monitoring to measure the policy impact [7]. The results provide information on the function of OS policies, whether they have the potential to act as vanguard of a cultural shift and how well they translate the principles to concrete research practices. [1] Nosek, B. (2019). Strategy for Culture Change. Center for Open Science. URL: https://www.cos.io/blog/strategy-for-culture-change [2] Weimer, V., Heck, T., Scherp, G., Hoenig, K., & Höffler, T. (2024). Open Science Policy Documents of the Leibniz Institutions. Open Science Festival 2024, Mainz. Zenodo. https://doi.org/10.5281/zenodo.13862317 [3] Leibniz Association (2022). Leibniz Open Science Policy. URL: https://www.leibniz-gemeinschaft.de/fileadmin/user_upload/Bilder_und_Downloads/Forschung/Open_Science/Open_Science_Policy.pdf [4] SPARC. (2018). An Analysis of Open Data and Open Science Policies in Europe. https://sparceurope.org/download/3674 [5] Chtena, N., Alperin, J. P., Morales, E., Fleerackers, A., Dorsch, I., Pinfield, S., & Simard,M.-A. (2023). The neglect of equity and inclusion in open science policies of Europe and the Americas. In SciELO Preprints. https://doi.org/10.1590/SciELOPreprints.7366 [6] Barcelona Declaration on Open Research Information, Kramer, B., Neylon, C., & Waltman, L. (2024). Barcelona Declaration on Open Research Information (1.0). Zenodo. https://doi.org/10.5281/zenodo.10958522 [7] European Commission: Directorate-General for Research and Innovation, Wouters, P., Ràfols, I., Oancea, A., Kamerlin, S. C. L. et al., Indicator frameworks for fostering open knowledge practices in science and scholarship, Publications Office of the European Union, 2019, https://data.europa.eu/doi/10.2777/445286