This article reviews pharmacological, animal, and human evidence regarding the abuse liability of methylphenidate (MPH). Findings are not always consistent, but evidence converges to suggest that although intravenous methylphenidate has some abuse potential, there is very little potential for oral MPH abuse. Furthermore, the available data suggests that children with Attention-Deficit/Hyperactivity Disorder (ADHD) who are treated with MPH are at lower risk for substance use disorder later in life. More longitudinal, prospective studies are needed to assess the long term effects of MPH treatment in ADHD.