There is increasing evidence that a proportion of children with Conduct Disorder may have unidentified Autistic Spectrum Disorder (Gilchrist et al., 2001 Gilmour, Hill, Place & Skuse, 2004). This paper considers the argument that a subgroup of children with Autistic Spectrum Disorder are undetected and subsumed under Conduct Disorder or similar descriptors. Diagnostic criteria are described and issues relevant to Conduct Disorder discussed. This is followed by an examination of the similarities and differences between Autistic Spectrum Disorder and Conduct Disorder. The case for misclassification of Autistic Spectrum Disorder is explored through reinterpretation of the behavioural markers associated with Conduct Disorder. Sample definition in studies of children with Conduct Disorder is then critically examined. The paper concludes with a review of the literature on social information processing in children with Conduct Disorder exploring whether some findings could be better explained by an Autistic Spectrum Disorder presentation.