The trial is a phase II/III randomized, double-masked, multicenter trial with a parallel treatment design. We will assign patients randomly to either etanercept or placebo in an assignment ratio of 1:1. In addition to either etanercept or placebo, we will treat all patients with standard drug regimens for WG according to the severity of their disease. We will treat those with limited WG with methotrexate and corticosteroids, and those with severe WG with cyclophosphamide and corticosteroids. After the patients' disease is controlled with therapy (i.e., the standard treatment regimen plus either etanercept or placebo), we will taper the standard medications according to regimens designed to ensure patient safety, diminish morbidity associated with the standard medications, and test the efficacy of etanercept in sustaining disease remissions.