The validity of the six-question World Health Organization Adult ADHD Self-Report Scale (ASRS) Screener was assessed in a sample of subscribers to a large health plan in the US. A convenience subsample of 668 subscribers was administered the ASRS Screener twice to assess test-retest reliability and then a third time in conjunction with a clinical interviewer for DSM-IV adult ADHD. The data were weighted to adjust for discrepancies between the sample and the population on socio-demographics and past medical claims. Internal consistency reliability of the continuous ASRS Screener was in the range 0.63–0.72 and test-retest reliability (Pearson correlations) in the range 0.58–0.77. A four-category version The ASRS Screener had strong concordance with clinician diagnoses, with an area under the receiver operating characteristic curve (AUC) of 0.90. The brevity and ability to discriminate DSM-IV cases from non-cases make the six-question ASRS Screener attractive for use both in community epidemiological surveys and in clinical outreach and case-finding initiatives. Copyright © 2007 John Wiley & Sons, Ltd.