The use of psychostimulants to treat attention-deficit/hyperactivity disorder (ADHD) has been controversial for a number of reasons. In an effort to clarify the extent to which the psychostimulant methylphenidate has abuse potential, the existing published evidence has been reviewed and is summarized here, with an emphasis on delineating a number of related but independent issues that are often confused. The existing evidence reviewed is pertinent to three questions: Does stimulant drug use increase the risk for substance abuse later in life? Do ADHD medications have the potential for abuse?, and What is the distinction between drug abuse and misuse/diversion with respect to ADHD medication?