The diagnostic process in child and adolescent psychiatry relies heavily on information from multiple informants, including parents, teachers, and the child itself. It has long been well known that information from informants who see the child in different settings may differ, but that each type of informant may contribute useful and unique information to the prediction of mental health problems.1 The diagnosis of attention-deficit/hyperactivity disorder (ADHD) depends on reports from informants who see the child in different settings. This is illustrated in the DSM-5, in which the diagnostic criteria require several inattentive or hyperactive-impulsive symptoms to be present in two or more settings.