This handbook is intended for anyone who wishes to host Open Science training events or introduce Open Science concepts to discipline-specific training events, in order to foster the uptake of open research practices. This includes researchers, librarians, infrastructure providers, research support officers, funders, policy makers and decision makers. This handbook is also meant for all those who have regular or occasional contact with researchers (and other stakeholders) and wish to share their Open Science knowledge, either as part of their regular working duties or as an extra investment of time. Importantly, it will be of use to those who wish to host training events to foster reuse, participation, efficiency, equity, and sharing in research, regardless of whether they ascribe to (or even wish to use) the term Open Science.