QUESTION ASKED: Is intensity of caregiving associated mentally unhealthy days (Fig). We also found that high with poorer mental health among cancer caregivers? Is hour/long duration caregivers reporting any unmet mental health worse among those whose support needs had a mean of 15 versus 5 unhealthy days for service needs are not being met? those with low hour/short duration with no unmet WHAT WE DID: We used data from the population-needs. based 2015 Behavioral Risk Factors Surveillance BIAS, CONFOUNDING FACTORS: Our study controlled System survey. We defined caregiving intensity as hours for sociodemographic factors known to be associated per week caregiving (high, . 20; low, # 20) and care-with mentally unhealthy days. Our study might be giving duration (long, . 2 years; short, # to 2 years). subjected to selection bias (those who participate in Mental health was self-reported as number of mentally the Behavioral Risk Factor Surveillance System unhealthy days in the past 30. Support service needs survey) and recall bias (difficulty recalling precise comprised caregiving classes, access to services, number of mentally unhealthy days, support service support groups, counseling, and respite care. needs, or caregiving experiences). WHAT WE FOUND: A total of 1,831 caregivers, repre-REAL-LIFE IMPLICATIONS: Our study found that high-senting 1.1 million across 18 states, were included in intensity cancer caregiving was associated with poor our study. We found that higher caregiving intensity mental health. Targeting support service provision for and support service needs were associated with more high-intensity cancer caregivers is warranted.