The current document, titled “Lessons learnt repository of TIME4CS: Building the TIME4CS knowledge base framework” has been developed within the structure of the TIME4CS project funded by the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No 101006201. This document synthesises the learnings of the case studies collected in Task 1.1 and the outcomes of D1.1 and D1.2, studying the Intervention Areas (IA) to define the key elements and drivers necessary for successful institutional transformation. For doing this, the present document summarises some of the most important points made throughout the previous work of TIME4CS (such as D1.2 Best practices repository of TIME4CS front-runners); defines the tailoring of a methodology for understanding the successful institutional transformation in support of citizen science in Research Performing Organisations (RPOs); describes some of the pathways for such a success in RPOs by detailing the results of the Fuzzy sets Qualitative Comparative Analysis (FsQCA) and links the resulting minimal formula with IA and grounding actions (a section for each IA domain) including different combinatory models to support the generation of a knowledge-based framework in support of citizen science in RPOs. The analysis shows that the path followed by RPOs with a higher level of Institutional Integration(InIn) of Citizen Science include the development of Citizen Science projects from different disciplines including but not limited to the Humanities, Natural Sciences, Biology/Ecology, Social Sciences and Multidisciplinary projects. In addition, having multiple Citizen Science champions seemed essential, this could be related to the fact that students and staff can provide the bottom-up pressure to push for institutional transformations; in addition, senior management citizen science champions can also influence the decision-making processes from top-down which would have a direct impact in modifying the structures in the organisations. Finally, the availability of an institutional plan that includes or considers Citizen Science and Public Engagement was a shared condition by those RPOs with higher institutional Integration. Having a Funded Coordinator appeared not to have a strong weight in supporting Institutional Integration and didn’t appear as part of the formula minimisation.