Background: Exercise is an important part of a healthy lifestyle for people with cystic fibrosis (CF). Exercise testing is also recommended as part of a routine assessment to provide physical activity counseling/exercise prescription. Body composition assessment is also an important assessment to can also guide dietary counseling. Prior studies have found that exercise testing and exercise training programs are underutilized in CF care centers, and no one has assessed the prevalence of body composition assessment. Thus, the purpose of this study was to develop and validate a survey to explore the barriers and facilitators that obstruct or promote the use of exercise and body composition testing in the CF care centers. Methods: Seventy-nine individuals with expertise in exercise and CF were invited to participate in a Delphi study. They rated the importance and quality of a 106-item survey on exercise and body composting testing and exercise training and shared their feedback. Results: Thirteen subject matter experts (SMEs) agreed to participate in the study, which lasted 3 rounds, but only 6 of them were in the final round. Of the 106 original items, 46 were kept with revisions, 58 were revised, 2 items were dropped, and 8 items were added, resulting in a final survey of 114 items. Conclusions: This Delphi study validated a survey to be used in CF care centers to provide valuable information about the benefits and barriers to exercise testing, exercise training, and body composition assessment in people with CF in the CFTR-modulator era.