Like usual interstitial pneumonia (UIP), nonspecific interstitial pneumonia (NSIP) is a pattern of lung injury with a variety of etiologies. NSIP is characterized by a more or less homogenous infiltrate of chronic inflammatory cells and/or fibrosis that widens and follows the original alveolar walls. Honeycombing is uncommon, as are fibroblast foci. Major etiologies of an NSIP pattern include connective tissue disease, hypersensitivity pneumonitis, and drug reactions. The prognosis of NSIP depends on the presence/absence of fibrosis: purely cellular forms do very well, whereas the more fibrosis, the worse the outcome, although fibrotic NSIP patients still have better survival than UIP/IPF patients.