Objective: In this article, the authors investigated the effectiveness of a behavior modification program using global positioning system (GPS) vehicle tracking devices with contingency incentives and disincentives to reduce the speeding behavior of drivers with ADHD. Method: Using an AB multiple-baseline design, six participants drove a 5-mile stable driving route weekly while GPS devices recorded speeds. The dependent variable was percentage of feet speeding. Following an initial baseline period, five participants received treatment. One participant remained at baseline. Results: Visual inspection of individual participant graphs, reductions in mean percentages of speeding from baseline to treatment across participants ("M" = 82%), "C"-statistic analyses, and visual graphs with applied binomial formula supported a treatment effect. The between-participant analysis using R[subscript "n"] Test of Ranks was significant, R[subscript "n"] = 6, p less than 0.01, and complemented a clean multiple-baseline result. Conclusion: Results indicated that this treatment program was effective in reducing speeding by drivers with ADHD and warrants replication. (Contains 5 figures and 1 table.)