A nursing school in Spain developed two massive open online courses (MOOCs) to train health professionals in patient safety. More than 12,000 people signed up for either one or both courses. The first course consisted of 8 modules focusing on the importance of training and establishing a safety culture, and the second course included 10 modules highlighting clinical safety in patient homes. About one-third of enrolled students completed each of the courses, an unusually high completion rate for a MOOC.