Twenty nine ADHD adolescents and 29 age, IQ and gender matched normal comparison subjects completed 6 paper pencil tasks of mental script generation. Each task required the subject to generate 10 chronologically ordered and necessary actions toward a goal. There were 3 levels of structure of the tasks (highly structured, moderately structured, unstructured) and each of these levels comprised a familiar and an unfamiliar script. The ADHD group made more sequencing errors on all the scripts, significantly so on the highly structured unfamiliar and on the moderately structured unfamiliar script tasks. The two groups were similar however with regard to the semantic structure (content) of the scripts and the total number of actions generated. Errors of omission, commission and perseveration were similar for the two groups. The results are interpreted as supportive of Barkley's (1997) frontal lobe dysfunction model of ADHD.