The biggest challenge in diagnosing nontuberculous mycobacterial (NTM) lung disease isn't confirmation; it's thinking to look for NTM in the first place. In this conversation with Dr. Brian McDonough, Dr. Doreen Addrizzo-Harris examines the subtle clinical and radiographic features that can help identify NTM earlier, discusses best practices for obtaining diagnostic cultures, and reviews how guideline-based criteria can help distinguish active disease from colonization. Dr. Addrizzo-Harris is the Fiona and Stanley Druckenmiller Professor of Pulmonary, Critical Care, and Sleep Medicine at NYU Grossman School of Medicine, as well as the Director of the Bronchiectasis and NTM Program at NYU Langone Health.