BACKGROUND: Specific domains of adaptive behaviours and academic achievement may, in part, depend on executive function capacities. Executive function deficits have been found to be associated with Attention Deficit Hyperactivity Disorder (ADHD), not Oppositional Defiant Disorder/Conduct Disorder (ODD/CD). METHOD: Using a sample of 110 adolescents, comprising four groups, ADHD only, co-morbid ADHD and ODD/CD, ODD/CD only, and a normal community control group, we assessed socialisation and communication skills with the Vineland Adaptive Behaviour Scales, along with reading ability, and executive functioning. RESULTS: Poorer adaptive communication skills were specifically associated with ADHD when compared with either ODD/CD or the control group, and the social competence of adolescents with ADHD was as low as the levels associated with ODD/CD. Presence of ADHD was associated with lower word recognition scores, while the reading levels of adolescents with ODD/CD were equivalent to those without behaviour problems. Executive function test scores correlated with all adaptive behaviour outcomes. Multiple regression analyses indicated that verbal ability predicted communication and reading scores, with executive function abilities contributing significant variance to the prediction in the adaptive behaviour, communication, and socialisation domains. CONCLUSIONS: Further research with other samples, both community and clinical groups, is needed to assess the generalisability of the findings. Small numbers of girls in the groups gave us insufficient power to adequately address potential gender differences.