PROJECT SUMMARY/ABSTRACT Numerous arguments have been advanced for the broad sharing of deidentified, participant- level clinical trial data. However, data sharing in the context of pragmatic clinical trials (PCTs) presents particular challenges. For example, prior debates about data sharing have largely focused on risks for individual research participants, yet sharing data from PCTs can also carry risks for health systems and for the clinicians within them—clinicians who may not have made a proactive decision to participate in the PCT, and who, in some cases, may be research subjects themselves. Furthermore, many PCTs are conducted with a waiver or alteration of informed consent, limiting the ability to align sharing decisions with the values and preferences of those individuals about whom information will be shared. Funders of PCTs, including the NIH HCS Collaboratory, NIH HEAL Initiative and the Patient- Centered Outcomes Research Institute, have recently developed policies and related resources to encourage data sharing.Yet how such policies are being implemented within individual PCTs, and the implications of these policies for the likelihood that PCT data will, in fact, be reused, remains poorly understood. The proposed research will develop empirically grounded evidence to support the responsible sharing of PCT data. In Aim 1, we will develop a conceptual model of the specific features of the PCT context that may influence the risk-benefit calculus for data sharing. This model will inform our Aim 2 work, which will explore the trade-offs presenting by data sharing in PCTs, as understood by those responsible for the oversight, creation, and future use of PCT data. In Aim 3, we will use a virtual conference with an expert advisory panel to evaluate the extent to which existing and proposed policies to promote data sharing are responsive to PCT-specific considerations. The contribution of this research will be significant because it will lay the essential groundwork for effective guidance regarding sharing of PCT data. This groundwork will advance the NIH Health Care Systems Research Collaboratory’s commitment to developing best practices for PCTs so as to maximize the National Institute of Health’s investments in embedded health research, and, ultimately to accelerate the pace of learning throughout the nation’s healthcare system.