van Emmerik–van Oortmerssen K, et al. – Author's purpose is to examine how a diagnostic assessment of Attention Deficit Hyperactivity Disorder (ADHD) in patients who are actively using substances compares to the results of a second assessment after a period of full or partial abstinence. The current study provides evidence that a pragmatic approach, in which patients are assessed for ADHD even when they are not (yet) abstinent, is feasible and justifiable.