Stimulant medications (amphetamine and methylphenidate) are the best-documented treatments for attention-deficit/hyperactivity disorder, but their short pharmacokinetic and behavioral half-lives have historically produced irksome time-course effects. New drug-delivery systems designed to eliminate the need for frequent dosing include the methylphenidate transdermal system, in which the matrix acts as both the drug reservoir and the skin adhesive. The methylphenidate transdermal system patch, in contrast to long-acting oral preparations, requires a paradigmatic shift in clinical thinking, as well as refinement of clinical management skills. For dosing with the methylphenidate transdermal system patch, clinicians must think in terms of a retrievable form of drug delivery (in milligrams per hour) rather than a fixed nonretrievable dose (in milligrams per dose or milligrams per day). Clinicians and patients can determine the optimal clinical dose by controlling 2 variables: (1) patch size (controlling milligrams per hour) and (2) duration of patch wear. The new paradigm is worth learning, because the patch offers several advantages over oral preparations for some patients, chiefly individualized control over effect duration (determined by when the patch is applied in the morning and removed in the afternoon/evening). Taking full advantage of this treatment option requires educating the patient and parents regarding practical elements of daily use. These elements include patch-site selection, application techniques, management of wear time to optimize the daily time course of clinical benefits, and skin hygiene. This article summarizes clinical principles that physicians may find useful in managing this new addition to the attention-deficit/hyperactivity disorder treatment armamentarium.