Years of heavy regulation and a long-standing focus on compliance have co-opted the ability of the healthcare industry to implement novel data sharing approaches. We now face a critical need for such innovation, as personalization and data science prompt patients to engage in the details of their healthcare and restore agency over their medical data. This thesis proposes MedRec: a novel, decentralized record man- agement system to handle EHRs (Electronic Health Records), using blockchain tech- nology. The system design gives patients a comprehensive, immutable log and access to their medical information across providers and treatment sites. Leveraging unique blockchain properties, MedRec manages authentication, data retrieval, update track- ing for existing records, data entry (both for patients and providers) and data shar- ing. MedRec accomplishes record management without creating any centralized data repositories; a modular system design integrates with providers' existing, local data storage solutions, facilitating interoperable data exchange between data sources and the patients. We incentivize healthcare industry stakeholders (government-funded re- searchers, public health authorities, etc.) to participate in the network as blockchain "miners". This provides them with access to aggregate, anonymized data as min- ing rewards, in return for sustaining and securing the MedRec network via Proof of Work. We emphasize the flexibility and extensibility of our system components to other dimensions of the healthcare industry and to applications beyond healthcare as well. This thesis describes the MedRec technical design and early-stage prototype, our pilot with Beth Israel Deaconess Medical Center (BIDMC), and an analysis of MedRec's contribution in the context of national healthcare priorities. This work is supported by the MIT Media Lab Consortium.