Approximately 135 adult male and female subjects with a confirmed diagnosis of Idiopathic pulmonary fibrosis (IPF) (according to the most recent IPF guideline for diagnosis and management) will be randomized 1:1:1 (45 subjects per arm) to treatment with oral CC-90001 (200 mg QD or 400 mg QD) or matching placebo for an initial 24 weeks. Subjects completing 24 weeks of treatment will continue onto the blinded 28-week Treatment Extension Phase. Following an initial screening at Visit 1, eligible subjects will be randomized to either CC-90001 200 mg or 400 mg PO QD or matching placebo beginning on Day 1 (Baseline Visit) of the study. Subjects completing the 24-week Double-blind Treatment Phase will continue the same blinded treatment assignment for 28 weeks in the Treatment Extension Phase. In the 28-week Treatment Extension Phase, all subjects will have the opportunity, if deemed appropriate by the Investigator, to use standard of care (SOC). The time to add and the choice of SOC will be at the Investigator's discretion. All subjects who complete the study treatment phases, or those subjects who discontinue Investigational product (IP) prior to the completion of the study, will participate in the 4-week Post-treatment Observational Follow-up Phase.