Older adults continue to spend little time engaged in physical activity when hospitalized. The purpose of this study was to (a) describe activity among hospitalized older adults with dementia and (b) identify the association between specific factors (gender, ambulation independence, comorbidities, race, and hospital setting) and their physical activity. This descriptive study utilized baseline data on the first 79 participants from the Function Focused Care for Acute Care using the Evidence Integration Triangle. Multiple linear regression models were run using accelerometry data from the first full day of hospitalization. The participants spent an average of 83.7% of their time being sedentary. Male gender, ambulation independence, and hospital setting (the hospital in which the patient was admitted) were associated with greater activity. This study reports on the limited time spent in activity for older adults with dementia when hospitalized and highlights patient profiles that are particularly vulnerable to sedentary behavior in the hospital setting.