Preface John R. Hurst It’s a pleasure to introduce this latest edition of the ERS Monograph, which addresses that most enigmatic of conditions: sarcoidosis. With myriad clinical manifestations, and multi-system involvement, there is a need for all clinicians – generalists and specialists alike – to have a working knowledge of the condition. This collection goes beyond a simple working knowledge, however, and I’d like to thank Guest Editors Francesco Bonella, Dominique Israël-Biet and Daniel A. Culver for commissioning and collating a comprehensive and excellent collection of state-of-the-art reviews, which provide a critical update on all aspects of sarcoidosis. The field is moving rapidly with new developments in both basic science and clinical practice, and therefore the collection is timely. I would also like to recognise the work of the individual chapter authors and reviewers for delivering this collection at a difficult time and, as always, the Monograph would not be possible without the dedicated support of the excellent ERS Publications Office. I learnt a lot about sarcoidosis reading these reviews, and I recommend them to you too. Disclosures: J.R. Hurst reports receiving grants, personal fees and non-financial support from pharmaceutical companies that make medicines to treat respiratory disease. This includes reimbursement for educational activities and advisory work, and support to attend meetings. Copyright ©ERS 2022. Print ISBN: 978-1-84984-145-0. Online ISBN: 978-1-84984-146-7. Print ISSN: 2312-508X. Online ISSN: 2312-5098. https://doi.org/10.1183/2312508X.10000822 v