PROJECT SUMMARY Efforts to create a cancer genomic commons are already underway, yet data sharing practices face daunting challenges. Ultimately, a genomic knowledge commons will only be successful if appropriate data-sharing poli- cies that address disincentives for sharing and implementation challenges are developed and mapped onto the institutions and actors who can enact such change. In an NHGRI-funded study (McGuire R01HG006460), a diverse group of experts ranked data-sharing as the most important, yet least politically tractable policy challenge among 17 posed in a modified Delphi process. The objective of this proposal is to engage expert advisors and relevant stakeholders to identify and rank challenges, generate policy solutions, and translate findings into action to ensure the success of a cancer genomic commons. Throughout the project, we will engage our expert multi- disciplinary advisory committee to solicit their input. In Aim 1, we will conduct a historical case study of the knowledge commons that exists in cancer genomics, as well as identify alternative frameworks for data sharing practices. In Aim 2, we will analyze the case study and conduct qualitative interviews with stakeholders in rele- vant constituencies to identify and further examine the challenges identified in Aim 1. In Aim 3, we will employ a policy Delphi process with advisory committee members to refine, rank, and generate solutions to key policy issues. This contribution will be significant because it will provide needed information to structure a cancer ge- nomics commons which are critical to the integration of genomic information in the management of inherited cancers. The approach is innovative by engaging a diverse and representative group of stakeholders, including those involved with and potentially contributing to these data initiatives, to identify policy challenges, generate solutions and map those to the appropriate institutions and actors. The work is feasible in our hands because our team of established investigators have expertise in ethical and policy issues related to large-scale data shar- ing and a track record of success working together on large collaborative projects addressing ethical and policy issues in genomics.