Adolescence is a time of significant physical, social, and emotional developments, accompanied by changes in cognitive and language skills. Underlying these are significant developments in brain structures and functions including changes in cortical and subcortical gray matter and white matter tracts. Among the brain regions that develop during adolescence are areas that are commonly damaged as a result of a traumatic brain injury (TBI). This paper summarizes major brain changes during adolescence and evidence linking maturation of these cognitive and language functions to brain development, placing consideration of both areas of development in the context of rehabilitation for adolescents with TBI.