Idiopathic pulmonary fibrosis (IPF) is a relentlessly progressive and typically fatal interstitial lung disease. Besides its grave natural history and prognosis, three aspects of IPF challenge clinicians and investigators: (1) recent changes in the conceptual framework and definition of IPF complicate interpretation of prior clinical investigations; (2) while most patients with suspected IPF do not undergo open-lung biopsy, clinical definitions that do not include biopsy criteria have not been validated prospectively; and (3) available treatments have not been shown to be effective. To optimize clinical care and facilitate clinical investigation, a major goal of IPF research should be to develop validated sets of clinical diagnostic and prognostic criteria. Studies have shown the diagnostic value of high-resolution CT scans and identified important prognostic variables; many of these observations await prospective validation. While previous therapeutic studies have been limited by small sample sizes, lack of a placebo control group, and insufficient attention to patient-centered outcomes, the recent study of interferon gamma-1b demonstrated the feasibility of a large-scale, multicenter clinical trial in IPF. In this article, we discuss how overcoming challenges in IPF research will enable future investigators to conduct well-designed observational studies and clinical trials, whose meaningful results will advance our understanding of IPF, its management, and its impact on patients' lives.