The Adverse Childhood Experiences (ACE) Study is a large epidemiological study that examines the impact of a broad range of childhood stressors on the health and social outcomes of adults. The aim of the current study was to examine the test-retest reliability of retrospective reports of adverse childhood experiences. In the current study, we used data from 658 participants who completed the ACE Study questionnaire on two separate occasions. We used Cohen's kappa to assess the test-retest reliability of adult reports of childhood sexual, physical, and emotional abuse; and forms of household dysfunction, including growing up with mental illness, substance abuse, parental discord or divorce, an incarcerated household member, and domestic violence. The test-retest reliability was conducted on both responses occurring during adulthood. This does not allow us to address the issue of whether or not there was a change in reporting from childhood to adulthood. Nonetheless, the results provide an overall indication that there is good to excellent reliability in the reports of adverse childhood experiences during adulthood. summary, we found the test-retest reliability in the responses to questions about adverse childhood experiences as well as the resulting ACE score to be good and moderate to substantial. These findings suggest that retrospective responses to childhood abuse and related forms of serious household dysfunction are generally stable over time.(PsycInfo Database Record (c) 2020 APA, all rights reserved)