In 2021, the Centre for International Governance Innovation (CIGI) organized a working group of its Global Platform Governance Network to focus on the issues of transparency and accountability of digital platforms, especially social media networks. Policy makers in many jurisdictions have concluded that social media companies have too much unchecked power and are failing to protect the public and their users from online harms. They are prepared to move forward with an ambitious reform agenda that includes focusing competition policy specifically on tech companies and addressing online safety issues. In many ways, transparency measures are low-hanging fruit in this new digital regulatory scheme, an area where different countries might agree even if they disagree on more controversial topics such as the mandated removal of harmful but legal material. CIGI held three online meetings to discuss the different aspects of these regulatory tools, which are mandated in many of the legislative proposals from different jurisdictions aiming to improve online safety. The objective was to share knowledge of the aims, methods, problems, strengths and weakness of new transparency and accountability regimes, and to work toward a common understanding of effective approaches. This report attempts to synthesize and summarize the discussions at these meetings. It is intended to be a contribution to the ongoing conversation of how to set up a flexible, agile regulatory regime that can learn from experience and respond to the evolving business and technological realities of the fast-changing digital landscape.