Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder and one of the main diagnoses seen by general paediatricians today. Despite the impression often portrayed in the media, it is not a new condition; in fact it has been described for over 200 years. The past 50 years has seen a progressive increase in our understanding of the underlying neurocognitive deficits in ADHD, and over the past 20 years behavioural genetics and neuroimaging studies have shed light on the complex causal factors and neurobiological processes operating. The plethora of ADHD research has advanced our knowledge of the condition, but so far has had little impact on improving clinical practice. Stimulant medication has been the mainstay of symptomatic treatment for over 30 years; however, it is still unclear how developmental trajectories can be modified to achieve best outcomes. It is hoped that novel therapies and more individualised management will evolve over the coming decades.