ERS | monograph Preface Robert Bals The field of ILD has gone through several years of change. Many old views on these diseases have been challenged and replaced by more convincing concepts. A good example is the change IPF therapy has undergone during recent years. According to the US philosopher Thomas S. Kuhn (1922–1996), progress in science often undergoes paradigmatic shifts rather than continuous progress. In clinical medicine, however, many examples show that continuous progress results in improved diagnosis or therapy. The field of ILD and IPF is somehow a mixture of both paradigm shift and continuous progress. Ongoing research in recent decades provided insight into disease mechanisms and underscored the heterogeneity and complexity of these diseases. A chance paradigmatic shift in IPF therapy followed the “crisis” finding that classical therapy with immunosuppressants was more dangerous than beneficial. In parallel, novel drugs were approved after their efficacy has been demonstrated in clinical trials. IPF is also a good example of a rare disease that needs special attention in the diagnostic process. However, if IPF is taken together with other ILDs, quite a high number of patients suffer from these conditions, meaning the whole disease area goes far beyond “rare” status. Interestingly, this field also gained much more attention when novel drugs became available pharmaceutical advertisements in this field certainly increased. The diagnosis and treatment of IPF is multidisciplinary, a fact that is well represented by the content and authors of this book. The book comprises chapters on molecular mechanisms, diagnosis, imaging, pathology and various aspects of therapy. It also reviews the fast developments in drug development. The critical use of data from clinical trials provides new ways to think about IPF and related diseases, and the shifted paradigms of recent years. The Guest Editors, Ulrich Costabel, Bruno Crestani and Athol U. Wells, have worked hard and very successfully to select these topics and to integrate these aspects Copyright ©ERS 2016. Print ISBN: 978-1-84984-067-5. Online ISBN: 978-1-84984-068-2. Print ISSN: 2312-508X. Online ISSN: 2312-5098. ERS Monogr 2016 71: v–vi. DOI: 10.1183/2312508X.10003316 v