The interstitial lung disorders are a heterogenous group of pulmonary disorders in which the interstitium is the predominant tissue type involved in the disease process. The idiopathic interstitial pneumonias represent a subgroup of these disorders that can be distinguished by unique clinical, radiologic, and pathologic features. Recent changes have been made in the classification system, with important distinctions between idiopathic pulmonary fibrosis and the other idiopathic interstitial pneumonias. Surgical lung biopsy remains the gold standard for diagnosis. However, controversy exists regarding the methods and indications for biopsy. In this article, we review the salient clinical, radiologic, and pathologic features of these unique disorders as well as the updated classification scheme. We also discuss the current methods, approaches, and indications for biopsy.