Diffuse parenchymal lung diseases (DPLDs) are a group of disorders that involve the space between the epithelial and endothelial basement membranes. Recent guidelines for the classification of DPLDs recommended separating patients into several categories, including (1) DPLDs of known cause, (2) granulomatous DPLDs, (3) rare DPLDs with well-defined clinicopathologic features, and (4) the idiopathic interstitial pneumonias (IIPs). The IIPs are further subdivided into categories that include usual interstitial pneumonia (idiopathic pulmonary fibrosis [IPF] if the usual interstitial pneumonia is idiopathic in origin) and nonspecific interstitial pneumonia. In numerous cohorts, IPF has been associated with impaired prognosis compared with nonspecific interstitial pneumonia, except in the setting of markedly impaired physiology at presentation. It is therefore imperative for the health care provider to rapidly assess the likelihood of a patient having IPF. The diagnostic approach has been refined over the past several years, with much clearer recommendations addressing the optimal clinical, radiologic, and laboratory assessments of patients with IIPs. Similarly, therapeutic interventions have rapidly evolved, with less emphasis on standard immunosuppression and increasing focus on interventions targeting fibroproliferation. Numerous therapeutic trials have recently been completed, are ongoing, or are soon to begin patient recruitment. A multicenter, National Institutes of Health-funded clinical research network has been convened to target novel therapeutic approaches in well-designed controlled trials. The next few years will be an exciting time in the evaluation and treatment of DPLDs as increasing clinically relevant biological information is translated to novel diagnostic and therapeutic approaches.