Physical and cognitive abilities are important for safe and successful participation in daily life, and much research has been done on how to preserve function in both kinds of ability throughout the aging process. Over the past twenty years these concepts were mostly studied separately; more recent research has led to new paradigms focused on the overlap in those brain mechanisms responsible for impairments in both mobility and cognition. A deeper understanding of this overlap could result in better interventions for maintaining the cognitive and physical health of older adults and a more comprehensive theoretical framework for understanding these complex, often integrated functions. This chapter (1) defines and describes cognitive and motor changes as part of the aging process, with a focus on individuals with dementia and mild cognitive impairment, (2) identifies methodologies used to understand the interrelationship between cognition and mobility, (3) describes what has been observed about this interrelationship, and (4) discusses research to date on potential interventions with suggestions for future interdisciplinary research.