Data from clinical trials, including participant-level data, are being shared by sponsors and investigators more widely than ever before. Some sponsors have voluntarily offered data to researchers, some journals now require authors to agree to share the data underlying the studies they publish, the Office of Science and Technology Policy has directed federal agencies to expand public access to data from federally funded projects, and the European Medicines Agency (EMA) and U.S. Food and Drug Administration (FDA) have proposed the expansion of access to data submitted in regulatory applications. Sharing participant-level data may bring exciting benefits for scientific research and public health but may also have unintended consequences. Thus, expanded data sharing must be pursued thoughtfully. We provide a suggested framework for broad sharing of participant-level data from clinical trials and related technical documents. After reviewing current data-sharing initiatives, potential benefits and risks, and legal and regulatory implications, we propose potential governing principles and key features for a system of expanded access to participant-level data and evaluate several governance structures.