Cognition is 1 of 4 domains measured by the NIH Toolbox for the Assessment of Neurological and Behavioral Function (NIH-TB), and complements modules testing motor function, sensation, and emotion. On the basis of expert panels, the cognition subdomains identified as most important for health, success in school and work, and independence in daily functioning were Executive Function, Episodic Memory, Language, Processing Speed, Working Memory, and Attention. Seven measures were designed to tap constructs within these subdomains. The instruments were validated in English, in a sample of 476 participants ranging in age from 3 to 85 years, with representation from both sexes, 3 racial/ethnic categories, and 3 levels of education. This report describes the development of the Cognition Battery and presents results on test-retest reliability, age effects on performance, and convergent and discriminant construct validity. The NIH-TB Cognition Battery is intended to serve as a brief, convenient set of measures to supplement other outcome measures in epidemiologic and longitudinal research and clinical trials. With a computerized format and national standardization, this battery will provide a "common currency" among researchers for comparisons across a wide range of studies and populations. Neurology Cognition is 1 of the 4 domains of behavioral and neurologic health assessed in the NIH Toolbox for the Assessment of Neurological and Behavioral Function (NIH-TB). All domain measures were intended to be freely accessible, to be usable with individuals from 3 to 85 years of age, with each domain battery not to exceed 30 minutes in duration. Expert surveys were conducted and panels of research scientists and clinicians consulted in an iterative manner to rank cognitive subdomains in order of their perceived importance for health. Information was requested from experts (N 5 102) who reported sufficient familiarity with cognition to make recommendations for specific subdomains of importance. The 2 top-ranked subdomains were Executive Function (EF) (95%) and Episodic Memory (93%), followed by Language (55%), Processing Speed (52%), and Attention (50%). Many (57%) also listed a "Global Score" as important. Other cognitive subdomains were excluded because of lower priority in the rankings, coupled with the stringent time constraints on the length of the battery.The rationale for specific cognitive constructs within subdomains and instrument selection was based on a systematic review of the literature, including evidence of the known biological associations of each. The EF subdomain was deemed to include several distinct constructs, including Switching/Set Shifting, Inhibitory Control and Attention, and Working Memory. Because of