There is a growing trend of libraries engaging their communities with information and open data by holding Wikipedia “edit-a-thons.” During the events, participants learn about the culture and norms of this widely used online resource by doing hands-on editing of articles, improving citations and adding new facts. The National Network of Libraries of Medicine (NNLM) held a health-focused edit-a-thon utilizing librarians’ research skills towards making Wikipedia a better and evidence-based resource in promoting NLM resources. Participants were able to view a customized training from Dr. James Hellman of WikiProject Medicine prior to the one-day event. On April 17, 2018 during the network wide online edit-a-thon, participants received online support from NNLM staff throughout the 12-hour event across the nation. At the end of the day, more than 700 edits were done in 111 articles focused on rare diseases. NNLM is planning similar events in future. This presentation will outline the planning process, marketing strategy, event details, evaluation, and future vision for this project.