Objectives Treatment decisions following severe acute brain injury need to consider patients' goals-of-care and long-term outcomes. Using family members as respondents, we aimed to assess patients' goals-of-care in the ICU and explore the impact of adaptation on survivors who did not reach the level of recovery initially considered acceptable. Design Prospective, observational, mixed-methods cohort study. Setting Comprehensive stroke and level 1 trauma center in Pacific Northwest United States. Participants Family members of patients with severe acute brain injury in an ICU for greater than 2 days and Glasgow Coma Scale score less than 12. Measurements and main results At enrollment, we asked what level of physical and cognitive recovery the patient would find acceptable. At 6 months, we assessed level of recovery through family surveys and chart review. Families of patients whose outcome was below that considered acceptable were invited for semistructured interviews, examined with content analysis. Results For 184 patients, most family members set patients' minimally acceptable cognitive recovery at "able to think and communicate" or better (82%) and physical recovery at independence or better (66%). Among 170 patients with known 6-month outcome, 40% had died in hospital. Of 102 survivors, 33% were able to think and communicate, 13% were independent, and 10% died after discharge. Among survivors whose family member had set minimally acceptable cognitive function at "able to think and communicate," 64% survived below that level; for those with minimally acceptable physical function at independence, 80% survived below that. Qualitative analysis revealed two key themes: families struggled to adapt to a new, yet uncertain, normal and asked for support and guidance with ongoing treatment decisions. Conclusions and relevance Six months after severe acute brain injury, most patients survived to a state their families initially thought would not be acceptable. Survivors and their families need more support and guidance as they adapt to a new normal and struggle with persistent uncertainty.