Under the sponsorship of Stanford University, we designed a massive open online course (MOOC) to raise public consciousness about the past, present, and future dangers of nuclear weapons. Most individuals—and many policymakers—remain blissfully unaware that risks such as nuclear terrorism, a regional nuclear war, or a nuclear conflict started by accident are higher today than during the Cold War. Our course, Living at the Nuclear Brink: Yesterday and Today, successfully appealed to a broad audience and increased discourse about this existential threat facing humankind. Consequently, we believe our experience lends insight into MOOCs in general, and demonstrates that they can be a powerful tool to create an informed citizenry.