Low physical activity (PA) and high sedentary behavior (SB) place residents in assisted living at risk for physical decline, but little is known about factors that influence PA/SB in this setting. In the current cross-sectional study, we described objectively measured PA/SB (activPAL™) and examined the relationships between PA/SB and use of an assistive walking device, depression, sleep disturbance, pain, fatigue, social isolation, and the tendency to make social comparisons. Fifty-four residents from eight assisted living facilities participated. Mean time spent in PA was 252.9 (SD = 134.3) minutes/day. Mean time spent in SB was 660.8 (SD = 181.4) minutes/day. Depression predicted PA (R2 = 0.16). Residents using an assistive device spent significantly more time in SB (p = 0.02). Fatigue correlated with time in longer bouts of SB (r = 0.19, p = 0.04). The tendency to make social comparisons correlated with SB (r = 0.22, p = 0.04). Findings show residents in assisted living are inactive and further research is needed to fully understand factors that influence PA/SB.