This report presents evidence on efforts taken by companies to ensure trust in the digital economy through transparency reporting. Focussing on the world’s most widely used social media platforms, online communication services, file-sharing platforms and other online services (many of which are based in the United States), the report identifies both good practices and challenges in transparency reporting. Challenges include limited informative value and comparability, as well as an inability to provide reliable information on the extent to which governments gain access to personal data held by the private sector. A range of actions are proposed to address these challenges, recognising the need to develop a more robust evidence base by expanding the number of countries and companies analysed. This report informed the review of the OECD Privacy Guidelines.