Devastating brain injuries (DBIs) profoundly damage cerebral function and frequently cause death. DBI survivors admitted to critical care will suffer both intracranial and extracranial effects from their brain injury. The indicators of quality care in DBI are not completely defined, and despite best efforts many patients will not survive, although others may have better outcomes than originally anticipated. Inaccuracies in prognostication can result in premature termination of life support, thereby biasing outcomes research and creating a self-fulfilling cycle where the predicted course is almost invariably dismal. Because of the potential complexities and controversies involved in the management of devastating brain injury, the Neurocritical Care Society organized a panel of expert clinicians from neurocritical care, neuroanesthesia, neurology, neurosurgery, emergency medicine, nursing, and pharmacy to develop an evidence-based guideline with practice recommendations. The panel intends for this guideline to be used by critical care physicians, neurologists, emergency physicians, and other health professionals, with specific emphasis on management during the first 72-h post-injury. Following an extensive literature review, the panel used the GRADE methodology to evaluate the robustness of the data. They made actionable recommendations based on the quality of evidence, as well as on considerations of risk: benefit ratios, cost, and user preference. The panel generated recommendations regarding prognostication, psychosocial issues, and ethical considerations.