Children with ADHD will often continue to have the disorder through adolescence, although individual symptoms may lessen or change, so their symptoms will need to be reassessed over time. In addition, adolescence is a transitional period in which youths experience new tasks and developmental challenges that may reveal impairments due to ADHD that were not apparent earlier. Evaluating for ADHD can be complicated by the differing symptoms seen in adolescents compared with children and the difficulty in obtaining a longitudinal history of symptoms. Various rating scales are available that can help clinicians to evaluate symptom frequency and severity and establish impairment when diagnosing adolescents with ADHD. Rating scales are also useful for establishing a baseline for symptoms, delineating individual symptoms as treatment targets, and measuring treatment success in patients with ADHD.