This large study found no increased risk of cardiovascular events in children and young adults using attention deficit–hyperactivity disorder (ADHD) drugs. Although the data are compatible with nearly a doubling of risk, the study was underpowered and the absolute event rate was quite low. Medications that are used to treat attention deficit–hyperactivity disorder (ADHD) are prescribed for more than 2.7 million children in the United States each year 1 and have been considered to be relatively safe. 2 – 5 However, reports of adverse events from Canada and the United States that have included cases of sudden death, myocardial infarction, and stroke in conjunction with the use of these drugs have raised concern about their safety. 6 , 7 Although case reports from adverse-event reporting systems can be an important source for identifying medication safety signals, they cannot reliably quantify risk. Thus, there is a compelling need to obtain . . .