Background Adverse childhood experiences (ACEs; i.e. child maltreatment, household dysfunction) have wide-reaching impacts and are strong predictors of poor outcomes in adults. However, many individuals who experience ACEs avoid or overcome their associated problems. The factors which effectively promote resilience against ACEs are still largely unknown.

Objective This research sought to understand what contributes to an individual’s resilience and how much resilience offers protection from the negative effects of ACEs.

Methods A face-to-face household survey was conducted with 2 497 residents aged 18–69 in Wales, United Kingdom, from March-June 2017. The survey explored: exposure to 11 ACEs; access to childhood and adult resilience resources, health-related behaviours and health outcomes.

Findings Half of all adults reported at least one ACE, 14% had four or more. ACEs were strongly associated with worse health outcomes, for example, individuals with 4+ACEs were four times more likely to report current mental illness, six times more likely to report lifetime mental illness and over nine times more likely to have ever felt suicidal or self-harmed. Childhood and adulthood resilience were associated with better health outcomes in those both with and without ACEs. Resilience resources associated with lower levels of mental illness included, in childhood: sports participation and having a trusted adult relationship; and as adults: sports/community group participation, enjoying culture/traditions, financial security, and higher perceived support from public services and employers.

Conclusion and policy implications ACEs are common and represent a significantly increased risk of poor health across the life-course. Supporting individuals affected by childhood adversity is vital to improve population health. Building resilience can moderate the increased risk to health that ACEs pose. However, resilience resources do not entirely counter ACE-related harms, thus work should be directed at the prevention of ACEs to ensure the provision of positive childhood environments for future generations.