Background: The current study examined the association of patient factors, patient/caregiver relationships, and living arrangements with caregiver burden due to delirium. Methods: The sample included a subset (N = 207) of hospitalized medical and surgical patients (aged >70 years) enrolled in the Better Assessment of Illness Study and their care-givers. Results: The majority of caregivers were female (57%) and married (43%), and 47% reported living with the patient. Delirium occurred in 22% of the sample, and delirium severity, pre-existing cognitive impairment, and impairment of any activities of daily living (ADL) were associated with higher caregiver burden. However, only the ADL impairment of needing assistance with transfers was independently significantly associated with higher burden (p < 0.01). Child, child-in-law, and other relatives living with or apart from the patient reported significantly higher caregiver burden compared to spouse/partners (p < 0.01), indicating caregiver relationship and living arrangement are associated with burden. Conclusions: Future studies should examine additional factors contributing to delirium burden.