Globalization of ADHD and the rise of cognitive enhancement have raised fresh concerns about the validity of ADHD diagnosis and the ethics of stimulant drug treatment. We review the literature on these two emerging phenomena, with a focus on the corresponding social, scientific and ethical debates over the universality of ADHD and the use of stimulant drug treatments in a global population of children and adolescents. Drawing on this literature, we reflect on the importance of ethically informed, ecologically sensitive clinical practices in relation to ADHD diagnosis and treatment.