OBJECTIVES: To evaluate the relationships between aging-related domains captured by geriatric assessment (GA) for older patients with advanced cancer and caregivers' emotional health and quality of life (QOL). DESIGN: In this cross sectional study of baseline data from a nationwide investigation of older patients and their caregivers, patients completed a GA that included validated tests to evaluate eight domains of health (eg, function, cognition). SETTING: Thirty-one community oncology practices throughout the United States. PARTICIPANTS: Enrolled patients were aged 70 and older, had one or more GA domain impaired, and had an incurable solid tumor malignancy or lymphoma. Each could choose one caregiver to enroll. MEASUREMENTS: Caregivers completed the Generalized Anxiety Disorder-7, Distress Thermometer, Patient Health Questionnaire-2 (depression), and Short Form Health Survey-12 (SF-12 for QOL). Separate multivariate linear or logistic regression models were used to examine the association of the number and type of patient GA impairments with caregiver outcomes, controlling for patient and caregiver covariates. RESULTS: A total of 541 patients were enrolled, 414 with a caregiver. Almost half (43.5%) of the caregivers screened positive for distress, 24.4% for anxiety, and 18.9% for depression. Higher numbers of patient GA domain impairments were associated with caregiver depression (adjusted odds ratio [aOR] = 1.29; P < .001], caregiver physical health on SF-12 (regression coefficient [β] = -1.24; P < .001), and overall caregiver QOL (β = -1.14; P < .01). Impaired patient function was associated with lower caregiver QOL (β = -4.11; P < .001). Impaired patient nutrition was associated with caregiver depression (aOR = 2.08; P < .01). Lower caregiver age, caregiver comorbidity, and patient distress were also associated with worse caregiver outcomes. CONCLUSION: Patient GA impairments were associated with poorer emotional health and lower QOL of caregivers. J Am Geriatr Soc 67:969-977, 2019.