There are considerable deficits in how scholarly knowledge is produced and disseminated. Open Science has the potential to change the workings of the scholarly communication system for the better. Openness, however, is a means to an end and within the scientific community, there is no commonly agreed set of principles that describe the system of scholarly communication that we want to create. Open Science is still a fuzzy concept for many; grounding it in a set of widely shared principles would make it much more understandable. The Vienna Principles and the Jussieu Call are two efforts into this direction. In my talk, I will point out commonalities and differences between the two charta and sketch how they can further a shared vision for open scholarly communication in collaboration with other initiatives.