The cognitive theory of obsessive-compulsive disorder (OCD) is the most widely accepted account of the aetiology and maintenance of this disorder in adults. This paper investigated whether cognitive processes were evident in a sample of children with a primary diagnosis of OCD. Using an idiographic approach, as proposed by the Obsessive-Compulsive Cognitions Working Group, this paper assessed cognitive appraisals of responsibility, probability, severity, thought-action fusion, self-doubt and cognitive control. Ratings of these cognitive appraisals were obtained across a sample of children with OCD, and were compared with ratings from a clinical control group of anxious children and a non-clinic control group. It was hypothesised that consistent with the cognitive theory of OCD, children in the OCD group would display higher estimations of these cognitive processes in comparison to anxious and non-clinic children. Results of this investigation provide preliminary support for a cognitive conceptualisation of OCD during childhood. OCD children reported significantly higher ratings of responsibility, severity, thought action fusion and less cognitive control in comparison to non-clinic children. OCD children could also be clearly differentiated from anxious children on ratings of cognitive control. Implications of this investigation are discussed and directions for future research are highlighted.