We assessed the strength of the association of several mental health problems, childhood difficulties, and combat role with anger, as well as the contribution of these factors to explain anger assessed by population attributable fraction (PAF). A total of 9885 UK service personnel, some of them deployed to Iraq and Afghanistan, participated in the study. There was a strong or intermediate association between cases and subthreshold cases of symptoms of posttraumatic stress disorder, psychological distress, multiple physical symptoms and alcohol misuse, having a combat role, childhood adversity, and childhood antisocial behavior with anger. The PAF for any mental health problem and combat role and childhood difficulties was 0.64 (95% confidence interval [CI], 0.56–0.70) and increased to 0.77 (95% CI, 0.69–0.83) if subthreshold cases were included. Anger is a frequent component of mental disorders; health care professionals need to be aware of the interference of anger in the management of mental illness and that anger infrequently presents as an isolated phenomenon.