Interstitial lung disease remains a cause of significant morbidity and mortality in patients with connective tissue disease associated ILD. While some patients meet clear classification criteria for a systemic rheumatic disease, there is a subset of patients not meeting classification criteria who still benefit from immunosuppressive therapy. In 2015, the American Thoracic Society and European Respiratory Society described classification criteria for interstitial pneumonia with autoimmune features (IPAF) to identify patients with lung predominant connective tissue disease who lack sufficient features of a systemic rheumatic disease to meet classification criteria. While these criteria are imperfect, they are an important attempt to classify the undifferentiated patient for future study. Rheumatologists play a key role in the evaluation of potential IPAF patients, especially as many patients with myositis spectrum disease (e.g. non-Jo1 anti-synthetase syndrome, MDA5 disease, and Pm-Scl disease) would be classified under IPAF using the currently available inflammatory myositis criteria and would benefit from rheumatologic co-management. This review aims to describe the historical context that led to the development of these criteria, limitations of the current criteria, diagnostic challenges, treatment options, and strategies for disease monitoring. This article is protected by copyright. All rights reserved.