The advancement of open science is no easy task. The many challenges to the implementation of open science (OS) policies in Higher Education (HE) institutions include lack of understanding, access, motivation, resources, and skills. Research libraries, being ideally positioned to serve as focal points for many OS initiatives, including citizen science (SC) projects, are no exception when it comes to the need for capacity development in the field of OS. Building on the expertise and experience of the research libraries��� community, this document represents a 10-step roadmap for capacity building on OS and CS for research libraries. The steps are thematically divided to address three major gaps that have been identified: resources, targeted communication, and structured training. The steps proposed in this roadmap can be adopted in their entirety or broken down to include only the relevant ones. The conceptualisation of these steps relied heavily on interaction with all the project���s intellectual outputs. Further attempts towards mapping the concepts developed within this roadmap were made through two highly interactive vision-building workshops in which a variety of stakeholders took part. The final discussion of these steps took place in the form of a co-creation workshop for the research libraries��� community, LIBER CS Working group and CS practitioners. This roadmap has been created to assist research libraries in developing their capacity to advance OS and adapt to changing environments and cultural shifts. This project has been funded with the support of the Erasmus+ programme of the European Union.