The risk of developing dementia increases with age. With the general public living longer, more strategies for promoting healthy aging and cognitive function will be critical. Many findings have shown that increased physical activity and the social environment play important roles in dementia prevention. However, the actual elements of a neighborhood environment--both physical activity and social environment--that promote healthy brain aging are uncertain. We hypothesized that individuals with greater neighborhood accessibility will have better cognitive function through more physical activity, walking, and social stimulation. This project aims to determine how neighborhood accessibility is associated with cognitive function and dementia among Portland area older adults using perceived and objective measures in 2004.