Sarcoidosis is a common-place multisystem disorder characterized by the presence of noncaseating granulomas. Although the clinical syndrome of the disease is recognized throughout the world, the pragmatic understanding of its diagnosis and management remains poorly understood and controversial. Much of the frustration experienced in elucidating its pathogenesis is directly related to our inability to find the cause of the disease. This article provides a brief and practical discussion of the diagnosis, pathogenesis, and concept of disease activity. It also recommends guidelines for management based on available clinical, immunologic, and radiological information enhanced by our experience at the University of Southern California during the past 30 years.