Health information exchange (HIE) offers tremendous potential for the future, but its widespread adoption and sustainability depend upon engaging patients and earning their trust. Patients' willingness to allow their data to be shared will drive the usefulness of HIE and therefore the sustainability of regional health information organizations (RHIOs). The Massachusetts eHealth Collaborative (MAeHC) is one of a few organizations that have developed a successful community-based collaborative model, with more than a 90 percent opt-in rate among patients to participate in widespread electronic data sharing. Lessons learned from MAeHC's three pilot programs could be instructive for other HIE projects around the country.