This self-directed learning module highlights the subpopulations of traumatic brain injury (TBI) that are treated by the rehabilitation practitioner. It is part of the chapter on TBI in the self-directed Physiatric Education Program for practitioners and trainees in physical medicine and rehabilitation. Specifically, this article focuses on the management of patients with mild TBI, children, and individuals with acquired brain injury from other etiologies, such as anoxic events or neoplastic lesions. The clinical spectrum of TBI, from the most severe presentation to the mildest, requires similar clinical skills to evaluate and manage. OVERALL ARTICLE OBJECTIVE: To describe the spectrum of brain injury populations based on age, severity, and etiology.