Childhood trauma is an important public health problem, but there are limitations in our ability to measure childhood abuse. The purpose of this study was to develop a self-report instrument for the assessment of childhood trauma that is valid but simple to administer. A total of 288 subjects with and without trauma and psychiatric disorders were assessed with the Early Trauma Inventory-Self Report (ETI-SR), an instrument for the assessment of physical, emotional, and sexual abuse, as well as general traumas, which measures frequency, onset, emotional impact, and other variables. Validity and consistency of the ETI-SR using different methods of scoring was assessed. The ETI-SR was found to have good validity and internal consistency. No method was found to be superior to the simple method of counting the number of items endorsed as having ever occurred in terms of validity. Some items were found to be redundant or not necessary for the accurate measurement of trauma severity within specific domains. Subsequent analyses with a shortened checklist of items showed acceptable validity and internal consistency. These findings suggest that the ETI-SR is a valid measure of early trauma, and suggest future directions for a shortened version of the ETI-SR that could be more easily incorporated into clinical research studies and practice settings.