This study will focus on an innovative complementary use of placebo. The purpose is to determine if pairing a placebo with stimulant medication produces a conditioned placebo response that allows children with ADHD to be maintained on a lower dose of stimulant medication. Conditioned placebo treatment would potentially enhance clinical care of children with ADHD by decreasing side effects. A sample of 80 children with ADHD will be recruited to participate in a three-phase study: (1) an initial double-blind dose finding phase to identify each child's optimal stimulant dose (2) a dose reduction phase to compare subjects randomly assigned to either conditioned placebo dose reduction (100 percent of dose PLUS placebo -> 50 percent of dose PLUS placebo) or dose reduction only condition (100 percent of dose -> 50 percent of dose), and (3) a treatment maintenance phase to examine the duration of conditioned placebo effects among positive responders. Treatment response will be measured by parent and teacher rating scales, objective measures of attention, and side effects. The conditioned placebo procedure to be examined involves daily pairing of the full stimulant dose with a visually distinctive placebo pill for 1 month followed by stimulant dose reduction with continuation of the placebo. This method carries the potential for eliciting a conditioned response as has been done in other medical treatment contexts that have demonstrated significant conditioned placebo responses (e.g. placebo treatment of pain). A visually distinctive placebo pill (color, size, and indicia distinct from the stimulant pill) will be used as previous research has shown that the visual characteristics of a placebo can enhance its positive effects. In a pilot study of placebo treatment in children with ADHD (n = 26) we found that approximately 40% of a sample of children with ADHD could be maintained on 50% of their typical dose of stimulant medication when dose reduction was accomplished using the conditioned placebo procedure. Specific aims of the proposed study are: (1) to determine the efficacy, side effects and acceptability of conditioned placebo treatment, (2) to examine specific treatment effects and persistence of effects over time, and (3) to identify predictors of conditioned placebo response.