ERS | monograph Preface John R. Hurst PR is an astonishingly effective intervention for improving the health of people living with chronic respiratory disease. It sounds so simple: exercise and education. Deceptively so. But underpinning widely recognised recommendations on how to establish, manage and evaluate PR classes sits a significant body of rigorous research, delivered through the diligence, patience and efforts of multi-professional clinical academics in the PR community. We owe them a great debt of thanks. We now know more about the science of PR than we ever have. And PR clinicians have risen to the challenge of delivering PR in evermore innovative ways following the reducted capacity for face-to-face classes during the COVID-19 pandemic. This issue of the Monograph is therefore both welcome and timely. It covers the topic comprehensively, from service set-up, through outcome measures, to patient experience. And this isn’t all about COPD or high-income settings: the evidence basis for PR is now much wider in both a disease-indication and geographical sense. As the Guest Editors note, for the benefits of PR to be fully realised, every clinician working in respiratory disease must understand how to recommend and refer people to PR, and to advocate strongly for widespread global provision. That task will be made much easier by understanding the evidence for PR, and this Monograph provides that state-of-the-art summary. I congratulate Anne E. Holland, Simone Dal Corso and Martijn A. Spruit on delivering this excellent collection, and the chapter authors for their authoritative summaries. Like all peer-reviewed publications, the efforts of reviewers often go unseen yet their role is vital. To you all, thank you. And to the reader: thank you for your support, enjoy the collection. 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 2021. Print ISBN: 978-1-84984-139-9. Online ISBN: 978-1-84984-140-5. Print ISSN: 2312-508X. Online ISSN: 2312-5098. https://doi.org/10.1183/2312508X.10010421 v