["Journal of Child Psychology and Psychiatry, Volume 67, Issue 5, Page 707-717, May 2026. ", "\n\nBackground\nChildhood adversity is associated with increased risks of long‐term social welfare dependence in young adulthood. Mental health problems may mediate this relation, but evidence remains lacking.\n\n\nMethods\n613,643 individuals from the Danish Life Course cohort (DANLIFE) were categorized into five trajectory groups based on their annual exposure to adversity: low adversity, early‐life material deprivation, persistent material deprivation, loss or threat of loss, or high adversity. Mental health problems were identified through hospital contacts and psychotropic medication use. Long‐term social welfare dependence was defined as receiving social benefits for at least 52 consecutive weeks within the follow‐up period. We examined the contribution of differential exposure and susceptibility to mental health problems in relation to childhood adversity and long‐term social welfare dependence through causal mediation analysis.\n\n\nResults\nThe different childhood adversity groups saw 54–319 additional cases of long‐term social welfare dependence per 1,000 individuals compared with the low adversity group. These associations were partly mediated through mental health problems. To illustrate, in the high adversity group, differential exposure to mental health problems accounted for 15.0% (95% CI: 14.4–15.6) of the total effect, while differential susceptibility accounted for an additional 9.8% (95% CI: 8.8–10.9).\n\n\nConclusions\nMental health problems partly mediate the relation between childhood adversity and long‐term social welfare dependence in young adulthood through both elevated exposure and increased susceptibility. Addressing mental health problems and increasing resilience among individuals with a history of childhood adversity may mitigate the risk of subsequent social welfare dependence.\n\n"]