BACKGROUND/AIMS: The purposes of this study were to examine the relationship between various objectively measured sedentary behavior (SB) variables and physical function in older adults, examine the measurement properties of an SB questionnaire, and describe the domains of SB in our sample. METHODS: Forty-four older adults (70 ± 8 years, 64 % female) had their SB measured via activPAL activity monitor and SB questionnaire for 1 week followed by performance-based tests of physical function. RESULTS: The pattern of SB was more important than total SB time. Where a gender by SB interaction was found, increasing time in SB and fewer breaks were associated with worse function in the males only. The SB questionnaire had acceptable test-retest reliability but poor validity compared to activPAL-measured SB. The majority of SB time was spent watching television, using the computer and reading. DISCUSSION/CONCLUSIONS: This study provides further evidence for the association between SB and physical function and describes where older adults are spending their sedentary time. This information can be used in the design of future intervention to reduce sedentary time and improve function in older adults.