Abstract Background Diagnosis and management of nontuberculous mycobacterial (NTM) lung disease is challenging for clinicians due to its rarity and the need for complicated, multidrug antibiotic regimens. The objective of this study was to determine whether online educational interventions can effectively address knowledge gaps among ID specialists regarding diagnosis and treatment of patients with NTM lung disease. Methods Two educational interventions, consisting of a text-based activity with interactive questions, and a video-based discussion between two experts, were developed and made available online. Educational impact of each intervention was assessed using a 3-question repeated pairs pre-/post-assessment study design. Data from a sampling of learners were collected from September 11, 2017 through January 17, 2018. Statistical analyses included a paired (within-physician) two-tailed t-test and McNemar’s χ2 statistic, with Cramer’s V to determine the overall effect of each intervention. Results Overall, a total of 1,273 ID specialist learners participated in the two activities from launch through April 30, 2018. Analysis demonstrated a significant improvement (P < 0.05) in overall knowledge with considerable educational impact (V = 0.195 and 0.259). Improvements in specific areas included (figure). Despite gains in knowledge, additional gaps were also identified: (1) Regarding treatment of M. abscessus lung disease, 18% were unable to discern between guideline recommended therapies for M. abscessus and MAC complex NTM, and an additional 14% would treat with a less aggressive, noncurative regimen (n = 211), and (2) regarding treatment of fibrocavitary MAC complex NTM; nearly one-third (31%) would treat a using a thrice-weekly regimen, despite an indication for a daily regimen (n = 114). Conclusion Participation in interactive text-based as well as video-based activities improved the ability of ID specialists to make evidence-based decisions in the care of NTM lung disease. The findings also uncovered educational needs that warrant further education in selecting appropriate therapeutic regimens particularly in cases where aggressive therapy is indicated. Disclosures E. Jackson, Medscape: Employee, Salary. P. Chatterjee, Medscape: Employee, Salary. S. Smith, BioFire Diagnostics: Independent Medical Education, Educational grant. K. Badal, Medscape: Employee, Salary. D. E. Griffith, Aradigm Corporation: Advisor/consultant and Speaker’s Bureau, Consulting fee and Speaker honorarium. Bayer Healthcare Pharmaceuticals: Advisor/consultant, Consulting fee. Grifols: Advisor/consultant and Speaker’s Bureau, Consulting fee and Speaker honorarium. Insmed Incorporated: Advisor/consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Grant recipient and Speaker honorarium.