The aim of the report „Transformative Agreements: Overview, Case Studies, and Legal Analysis” is to present the current situation regarding ‘transformative agreements’ understood as a means of transitioning from a subscription-based model of scientific publishing to full and immediate open access. In chapter one, the authors present transformative agreements in the context of Plan S; in chapter two, they outline the current state of negotiations and agreements between scientific institutions and publishers in various countries; in chapter three, they provide legal analysis of the agreements from the ESAC Transformative Agreement Registry. Chapter four consists of three case studies (Germany, Norway, Sweden); finally, chapter five is devoted to recommendations. The report, edited by Jakub Szprot and Natalia Gruenpeter, was prepared as part of the Open Science Platform activities by a team of authors from the Interdisciplinary Centre for Mathematical and Computational Modelling at the University of Warsaw (Natalia Gruenpeter, Nikodem Rycko, Krzysztof Siewicz, Jakub Szprot). Case studies: Germany: Ralf Schimmer, Colleen Campbell, Max Planck Digital Library Norway: Nina Karlstrøm, Nils Andenæs, The Norwegian Directorate for ICT and Joint Services in Higher Education and Research (Unit) Sweden: Anna Lundén, Britt-Marie Wideberg, National Library of Sweden Update, 5.03.2021: A revised version (version 2) was uploaded. In the previous version, there was an error in Figure 1 (page 33). In the legend to the graph, the last row was omitted. It should appear as follows: turquoise - American Chemical Society (ACS), pink - Georg Thieme Verlag KG (see page 33).