This special edition of Rehabilitation Psychology (Volume 62, Issue 4) provides an in-depth look at the NIH Toolbox Cognition Battery and its use in populations with disabilities. When the NIH Toolbox was first developed, its goal was to provide researchers and clinicians with a universal language in which they could make comparisons about cognitive, motor, sensory, and emotional health and functioning. However, the NIH Toolbox norming efforts focused on the general population of children and adults and not specifically on those with disabilities, reducing its clinical use applicability. Now, our research team has taken on the critical task of evaluating the clinical utility and construct validity of the NIH Toolbox in persons with disabilities, focused on those with traumatic brain injury, spinal cord injury, stroke, and other neurological conditions.