BACKGROUND: Mass critical care entails time-sensitive decisions and changes in the standard of care that it is possible to deliver. These circumstances increase provider uncertainty as well as patients' vulnerability and may, therefore, jeopardize disciplined, ethical decision-making. Planning for pandemics and disasters should incorporate ethics guidance to support providers who may otherwise make ad hoc patient care decisions that overstep ethical boundaries. This article provides consensus-developed suggestions about ethical challenges in caring for the critically ill or injured during pandemics or disasters. The suggestions in this article are important for all of those involved in any pandemic or disaster with multiple critically ill or injured patients, including front-line clinicians, hospital administrators, and public health or government officials. METHODS: We adapted the American College of Chest Physicians (CHEST) Guidelines Oversight Committee's methodology to develop suggestions. Twenty-four key questions were developed, and literature searches were conducted to identify evidence for suggestions. The detailed literature reviews produced 144 articles. Based on their expertise within this domain, panel members also supplemented the literature search with governmental publications, interdisciplinary workgroup consensus documents, and other information not retrieved through PubMed. The literature in this field is not suitable to support evidence-based recommendations. Therefore, the panel developed expert opinion-based suggestions using a modified Delphi process. RESULTS: We report the suggestions that focus on five essential domains: triage and allocation, ethical concerns of patients and families, ethical responsibilities to providers, conduct of research, and international concerns. CONCLUSIONS: Ethics issues permeate virtually all aspects of pandemic and disaster response. We have addressed some of the most pressing issues, focusing on five essential domains: triage and allocation, ethical concerns of patients and families, ethical responsibilities to providers, conduct of research, and international concerns. Our suggestions reflect the consensus of the Task Force. We recognize, however, that some suggestions, including those related to end-of-life care, may be controversial. We highlight the need for additional research and dialogue in articulating values to guide health-care decisions during disasters.