Many resources currently available for graduate and undergraduate medical education are fragmented, difficult to access, and costly. Osmosis, a web- and mobile-based platform, was developed to create a shared and easily accessible repository of curated clinical educational resources. We have recently launched “Open Osmosis” - a public-facing portal that has become one of the largest databases of Creative Commons-licensed questions, among other open educational resources (OER), for medical education. Initially created for use at the Johns Hopkins School of Medicine, Osmosis spread to recruit and involve medical students, physicians, and clinical content advisors from dozens of countries and hundreds of institutions. These individuals have served various roles, including as question-writers (“Medical Contributors”), content organizers (“Medical Scholars”), and expert reviewers (“Clinical Advisors”). Here we describe our experience developing Open Osmosis as a case study for crowdsourcing medical education content, and to comment on potential future development of this platform.