230 Background: Informal/family caregivers play a critical role in supporting cancer patients and are often an important part of the palliative care team. To better understand how informal caregivers are influenced by their role and inform future interventions, this study sought to evaluate the distribution and correlates of social and family factors among caregivers of cancer patients. Methods: This cross-sectional study used data from the Cancer Care Outcomes Research & Surveillance Consortium (CanCORS). Lung and colorectal cancer patients nominated an informal caregiver to participate in a caregiving survey. Caregivers reported their sociodemographic and caregiving characteristics, social stress, relationship quality with the patient, and family functioning. Descriptive statistics were used to assess the distribution of caregivers’ social factors. Multivariable linear regressions were used to examine the independent correlates of each social factor. Results: Most caregivers reported low-to-moderate levels of social stress and good relationship quality and family functioning. In multivariable analyses older age was associated with lower social stress and better family functioning, but worse relationship quality, with effect sizes (Cohen’s D) up to 0.40 (p < 0.05). Caring for a female patient was associated with lower social stress and better relationship quality, but worse family functioning (effect sizes up to 0.16, p < 0.05). Few caregiving characteristics were associated with social stress, while several were significant independent correlates of relationship quality. Finally, social factors were important independent correlates of one another. Conclusions: The results highlight the importance of personal and caregiving-related characteristics and the broader family context to social factors. As social factors may play an important role in the health, quality of life, and caregiving efficacy of informal caregivers, future work is needed to better understand these pathways and assess whether interventions targeting social factors can improve caregiver well-being, thereby potentially improving patient-centered palliative care.