In this second of four special episodes highlighting the USCAP 2021 Long Course on Pulmonary Pathology, our host is joined by two distinguished faculty: Dr. Andrew Churg of the University of British Colombia and Dr. Maxwell Smith from the Mayo Clinic Arizona. The two international experts on interstitial lung disease (ILD) share their valuable perspective on "where we are and where we need to go" in our approach to the diagnosis and classification of hypersensitivity pneumonitis (HP) and usual interstitial pneumonitis (UIP).