The association of neighborhood built environment with walking activity has received growing attention, although most studies have relied upon subjective measures of the built environment and few have examined the relation between built environment and walking among older adults. This 2001 study examined the relation between objectively measured characteristics of the local neighborhood and walking activity among a sample of 546 community-dwelling older adults in Portland, Oregon. A geographic information system was used to derive measures of the built environment within a quarter-mile (0.4 km) and half-mile (0.8 km) radius around each participant's residence. Multilevel regression analysis was used to examine the association of built environment with walking behavior. No association between built environment and the likelihood of walking or not walking was observed in this cohort of older adults. However, among those participants who reported some degree of walking activity, average time spent walking per week was significantly associated with amount of automobile traffic and number of commercial establishments in their local neighborhood. These findings suggest that built environment may not play a significant role in whether older adults walk, but, among those who do walk, it is associated with increased levels of activity.