PathOS (Open Science Impact Pathways) is a Horizon Europe project aiming to gather concrete evidence of the impacts of Open Science (OS). It seeks to understand the progression from input to output, outcome, and eventual impact, taking into account both enabling factors and critical barriers. The project centers its activities around six targeted case studies that will: (a) drive the modelling of the pathways with all relevant elements of OS which can be measured both in terms of indicators for input and costs, and by making their connections (b) support testing and operationalization of OS indicators (tools, data, flows) by providing access to data and experts who bring knowledge of the local environment, and (c) provide input to a Cost Benefit Analysis framework and to validate project results This poster will highlight the PathOS Impact Pathways, illustrating the project’s assessment and categorization of Open Science impacts. Each of the six case studies will be aligned with these pathways, showing diverse Open Science applications emphasizing how they enhance access to scientific information. Preliminary results will be presented through informative graphs, demonstrating the effectiveness of open access principles in various research contexts. This section will not only show quantitative metrics but also provide insights into how open access policies are being practically implemented in each case. The second part of the poster will compare the PathOS findings with existing literature on Open Science, situating the project within a broader academic discourse. ‘Indicator bubbles’ for each case study will be included, highlighting specific Open Science impacts that will be examined. By doing so, the poster will illustrate how Open Science practices, as investigated in the PathOS project, are transforming research environments and learning modalities in academic settings. By presenting tangible examples and insights derived from the PathOS methodological approach and real-life application of the case studies, we intend to showcase valuable perspectives on monitoring the impact of Open Science, thereby providing essential resources for research libraries committed to embracing and upholding Open Science principles and practices. References: PathOS Case studies: https://pathos-project.eu/case-studies Open Science Intervention Logic Report: https://zenodo.org/records/10418573 Case studies for evaluation of open science impact: https://zenodo.org/records/10057051 Scoping Review of Open Science Impact: https://zenodo.org/records/7969951