This is a Phase 2, multicenter, multinational, randomized, double-blind, placebo-controlled study evaluating the efficacy, safety, pharmacokinetics (PK), quality of life and exploratory pharmacodynamics (PD) of two treatment doses of CC-90001, 200 mg and 400 mg, compared with placebo, when delivered once daily per os (PO) in subjects with idiopathic pulmonary fibrosis (IPF). This study is designed to assess response to treatment by using measures of lung function, disease progression, fibrosis on radiography, and patient-reported outcomes. It will also assess dose response.