Project Summary/Abstract Declining mobility function is a common age-related phenomenon that is associated with reduced quality of life and high societal costs. Recently, the brain's critical role in mobility function has been recognized using imaging approaches assessing white matter characteristics. A new paradigm considering the brain as acomplex network uses MRI-based approaches to directly characterize the brain as a functional network. Brain Networks and Mobility Function: B-NET brings together national leaders in brain network science and mobility assessment to apply this innovative network paradigm to elucidate the brain's role in declining mobility. We propose that changes in functional connectivity within and between brain regions supporting movement predict declining mobility. We hypothesize that age-related structural damage affects mobility, in part, by degrading the community structure of sensorimotor cortex (SMC) reflected in lower SMC modularity and increased SMC connectivity to other brain regions. B-Net established a cohort of 192 community-dwelling older adults (age range 70-85) and measure mobility function at baseline, 6, 18 and 30 months using the extended short physical performance battery (eSPPB) to address the following specific aims.