Background: Chronic obstructive pulmonary disease (COPD) is an important cause of morbidity and mortality in the U.S. However, little is known about the influence of childhood stressors on its occurrence. Methods: Data were from 15,472 adult HMO members enrolled in the Adverse Childhood Experiences (ACE) Study from 1995 to 1997 and eligible for the prospective phase. Eight ACEs were assessed: abuse (emotional, physical, sexual); witnessing domestic violence; growing up with substance-abusing, mentally ill, or criminal household members; and parental separation or divorce. The number of ACEs (ACE Score) was used to examine the relationship of childhood stressors to the risk of COPD. Three methods of case ascertainment were used to define COPD: baseline reports of prevalent COPD, incident hospitalizations with COPD as a discharge diagnosis, and rates of prescription medications to treat COPD during follow-up. Follow-up data were available through 2004. Results: The ACE Score had a graded relationship to each of three measures of the occurrence of COPD. Compared to people with an ACE Score of 0, those with an ACE Score of ≥5 had 2.6 times the risk of prevalent COPD, 2.0 times the risk of incident hospitalizations, and 1.6 times the rates of prescriptions (p<0.01 for all comparisons). These associations were only modestly reduced by adjustment for smoking. The mean age at hospitalization decreased as the ACE Score increased (p<0.01). Conclusions: Decades after they occur, adverse childhood experiences increase the risk of COPD. Because this increased risk is only partially mediated by cigarette smoking, other mechanisms by which ACEs may contribute to the occurrence of COPD merit consideration.