Objective: To revise the 1999 Airlie House consensus guidelines for the design and implementation of preclinical therapeutic studies and clinical trials in amyotrophic lateral sclerosis (ALS). Methods: A consensus committee comprising 140 key members of the international ALS community (ALS researchers, clinicians, patient representatives, research funding representatives, industry and regulatory agencies) addressed nine areas of need within ALS research: 1. Pre-clinical studies; 2. Biological and phenotypic heterogeneity; 3. Outcome measures; 4. Disease-modifying and symptomatic interventions; 5. Recruitment and retention; 6. Biomarkers; 7. Clinical trial phases; 8. Beyond traditional trial designs; and 9. Statistical considerations. Assigned to one of eight sections, committee members generated a draft set of recommendations based on a “background” of developing a (pre)clinical question and a “rationale” outlining the evidence and expert opinion. Following a two-day, face-to-face workshop at the Airlie House Conference Center, a modified Delphi process was used to develop draft consensus guidelines, which were subsequently reviewed and modified based on comments from the public. Statistical experts drafted a separate document of statistical considerations (section 9). Results: In this paper we summarize 112 recommendations and their associated backgrounds and rationales. The full list of recommendations on all main topics as well as on statistical considerations are available (Appendices e-3 and e-4). The authors prioritized 15 recommendations with the greatest potential to improve ALS clinical research. Conclusion: The revised Airlie House ALS Clinical Trials Consensus Guidelines should serve to improve clinical trial design and accelerate the development of effective treatments for patients with ALS.