The current document, titled “Best practices repository of TIME4CS front-runners” has been developed within the framework of the TIME4CS project which is funded by the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No 101006201. The main objectives of the document are to: Analyse each Front-Runner to describe which actions were required to implement Institutional Changes and to promote citizens’ engagement in R&I activities within their organisation; expand the number and the kind of possible Grounding Actions; share the best practices of institutional adoption of public engagement and Citizen Science that Implementers can include in their roadmaps. To this end, the document analyses the history and activity of the Front-Runners since their establishment, and maps their activities with the identified Intervention Areas and Grounding Actions. The result of this process is the identification of the best practices that allowed Front-Runners to succeed in achieving the changes necessary to have Public Engagement and Citizen Science promoted and supported at the Institutional level.