We are currently witnessing a fundamental structural transformation of the scientific public sphere, characterized by processes of specialization, metrification, internationalization, platformization, and visibilization. In contrast to explanations of this structural transformation that invoke a technological determinism, we demonstrate its historical contingency by drawing on analytic concepts from organization theory and the case of the Open Access transformation in Germany. The digitization of academic journals has not broadened access to scientific output but narrowed it down even further in the course of the “serials crisis”. For a long time, research institutions were not able to convince large academic publishers to adopt less restrictive forms of access to academic journals. It was only through the emergence of new and in part illegal actors (shadow libraries and preprint servers) that the existing path could be broken, and an Open Access path constituted. Following this analysis, we discuss consequences of the Open Access transformation for the public spheres of science and democracy. We conclude that Open Access publishing can only help to transform both communicative spaces towards the normative ideal of a public sphere when complemented by systematic support for non-profit publication infrastructures.