Abstract: The nature and prevalence of pragmatic language deficits were investigated in conversations of 137 adolescents with their mothers. Adolescents diagnosed with Attention-Deficit/Hyperactivity Disorder (ADHD) or ADHD comorbid with ODD or CD demonstrated more problems with pragmatic language than the comparison group of normally developing adolescents (NC). Deficits and impairment were measured using summary scores on both scales of the Profile of Pragmatic Impairment in Communication. Adolescents were observed in video-taped conversations in two situations: neutral, planning a hypothetical family vacation, and conflict, solving behavior problems identified by their mothers. The computed Mean Length of Utterance was used to measure the youths' level of talkativeness. Results confirmed that ADHD youth talked more than NC youth. Differences were found between ADHD and ADHD-ODD adolescents' behavior in the conflict situation. Results also illustrated the need for the assessment of pragmatic language skills in children and youth diagnosed with ADHD.