Objective: To investigate the effects of methylphenidate on long-term executive and neuropsychological functioning in children with attention problems following TBI, as well as the relationship between methylphenidate associated changes in lab-based neuropsychological measures of attentional control, processing speed, and executive functioning and parent- or self-report measures of everyday executive functioning. Method: 26 children aged 6–17 years, who were hospitalized for moderate-to-severe blunt head trauma 6 or more months previously, were recruited from a large children’s hospital medical center. Participants were randomized into a double-masked, placebo-controlled cross-over clinical trial. Participants completed a comprehensive neuropsychological battery and parent- and self-report ratings of everyday executive functioning at baseline, and at 4 weeks and 8 weeks following upward titration of medication to an optimal dose or while administered a placebo. Results: Methylphenidate was associated with significant improvements in processing speed, sustained attention, and both lab-based and everyday executive functioning. Significant treatment-by-period interactions were found on a task of sustained attention. Participants who were randomized to the methylphenidate condition for the first treatment period demonstrated random or erratic responding, with slower and more variable response times when given placebo during the second period. Conclusion: Results indicate that methylphenidate treatment is associated with positive outcomes in processing speed, sustained attention, and both lab-based and everyday measures of executive functioning compared to placebo group. Additionally, results suggest sustained attention worsens when discontinuing medication. (JINS, 2019, 25, 740–749)