The purpose of this study was to assess physical reserve (PR) in 15 independent community dwellers (IND) and 15 marginally dependent adults (MDEP) ??70 years. We hypothesized that PR would be higher in the IND group and would be significantly related to physical function. Dependent variables were Continuous Scale Physical Functional Performance (CS-PFP) total score, and oxygen consumption during graded treadmill walking (VO2peak), physical functional performance (VO2PFP) and usual gait (VO2gait). The primary outcome, PR, was determined from physical functional performance (PR-PFP) and usual gait (PR-Gait). After covariating for age, there was a significant difference (p<0.05) between groups for PR-PFP, CS-PFP total score, and VO2peak; VO2PFP and VO2gait were not significantly different. PR was significantly related to physical function. Improving PR may improve physical function in marginally dependent older adults and provide independent older adults a larger margin of safety.