Background: Family caregivers of persons with cancer are at high risk for distress and may benefit from formal support services. The purpose of this study was to describe cancer family caregiver’s use of and desire for formal support services. Methods: Cross-sectional mail survey conducted in communities of eight cancer centers in Tennessee, Alabama, and Florida. Family caregivers of Medicare beneficiaries with pancreatic, lung, brain, ovarian, head and neck, hematologic, and stage IV cancers reported support service use and completed validated measures of depression, anxiety, burden, preparedness, and health. Results: Caregivers(n = 294) were on average age 65.5 years and mostly female (72.8%), white (91.2%), and care recipients’ spouse/partner (60.2%). Patients averaged 75.3 years and were mostly male (54.4%). Formal support services were used by 32.0% (n = 94) of all caregivers; 4.4% used therapy or counseling, 19.7% received education and training; and 11.2% received assistance from local, state, or national organizations. Twenty-eight percent of all caregivers were “mostly or “extremely” interested in receiving support services; of those, 44% had high depressive symptoms, 52.3% had high anxiety symptoms, and 36.4% in the lowest quartile of preparedness. In multivariate analyses, participation in services was significantly associated with lower objective burden, higher preparedness, not working, and not being the patient’s spouse. Being “mostly” or “extremely” interested in support services was significantly associated with being a minority, shorter durations of caregiving, and with higher stress burden. Conclusions: While distressed and underprepared family caregivers reported strong interest in formal support services, only a small proportion accessed these services. Strategies to increase service use may include targeting those caregivers who are still early in their caregiving experience and who report high stress burden.