Background. There is increasing interest in measuring the quality of survivorship for patients admitted to the intensive care unit for acute respiratory failure (ARF). However, there is substantial variability in patient outcomes reported in studies evaluating these patients, with few data on which outcomes are essential to inform clinical practice. Objective. The objectives of this study were to determine clinicians’ perspectives on the outcome domains that should always be reported in studies evaluating people who have had ARF after hospital discharge and to compare findings about US and Australian perspectives. Design. A modified Delphi method was used for the study. Methods. A survey with 19 possible domains was developed to iteratively elicit clinicians’ perspectives on core outcome domains via a modified Delphi method. The survey was initially administered online. The survey results were then discussed independently at meetings at scientific conferences in the United States and Australia, and the survey was repeated at the meetings after the discussions. Results. The numbers of participants who responded to both the online and the real-time polling were 44 of 100 (44%) in the United States and 78 of 85 (92%) in Australia. Most respondents were intensive care unit–based clinicians (United States: 33 [75%]; Australia: 76 [97%]). For the 19 domains evaluated, both US and Australian groups ranked physical function and symptoms as the most important domain, with quality of life, cognitive function and symptoms, and survival being the next 3 most important domains. These data yielded a total of 4 domains meeting the criteria for inclusion as core domains at both meetings. Limitations. Several key constituencies, including patients and caregivers, were not represented in this study; their perspectives are also important and ideally should be included in the development of a comprehensive core outcome set. Conclusions. Clinicians agreed that physical function and symptoms, quality of life, cognitive function, and survival were domains that should always be measured in research evaluating outcomes for people who have had ARF after hospital discharge.