Overall Project Summary: Aging-associated cognitive decline, whether mild or severe, can profoundly affect the independence, well-being, and quality of life of those aged 65 and older. Development of effective interventions and treatments for this requires standard, psychometrically sound, easy-to-use measures that are sensitive to early indicators of cognitive decline and also capture non-cognitive factors associated with or predictive of cognitive changes. ?Advancing Reliable Measurement in Alzheimer's Disease and cognitive Aging? (ARMADA) proposes to meet this need by validating and expanding the NIH Toolbox for Assessment of Neurological and Behavioral Function (NIHTB) for use in studies of cognitive aging beginning with normal cognition through progression into mild cognitive impairment and into early stages of Alzheimer's dementia. The NIHTB, developed with NIH support, provides a multidimensional, state-of-the-art set of measurement tools (available in English and Spanish) assessing key aspects of cognitive, sensory, motor, and emotional function and validated and normed in the general population for ages 3-85 years. To ensure that the NIHTB will be a valuable resource for cognitive aging research we will: 1) Validate English and Spanish versions of an expanded NIHTB (the NIHTB+) in existing, well-characterized, ethnically and racially diverse samples of adults ages 65-85 representing the trajectory of cognitive aging and in cognitively normal individuals 86+ years of age. 2) Expand the NIHTB by adding innovative instruments to assess neurological functions associated with cognitive aging; and 3) Facilitate use of the NIHTB+ in aging research by ensuring it is a readily available resource with robust user support. In order to accomplish these aims, we will form a consortium with the National Alzheimer's Coordinating Center (NACC) and with researchers in cognitive aging and dementia from Alzheimer's Disease Centers and other clinical sites with existing cohorts. The consortium will be supported by Administrative, Technical, and Data and Statistical Analysis Cores.