Behaviour Change 28(3): 128-142 Abstract Objective: This study aimed to extend current research into cognitive models of obsessive-compulsive disorder (OCD) in a pediatric sample by examining the impact of perceived responsibility on memory confidence, intolerance of uncertainty (IU) and checking urge using an experimental design to manipulate perceived responsibility. It was hypothesised that the high responsibility condition would result in higher ratings of responsibility, lower memory confidence and higher IU, which would also result in higher ratings on urge to check. Moreover, it was hypothesised that adolescents would report significantly higher ratings of responsibility than children. Finally, it was hypothesised that the effect of perceived inflated responsibility on the urge to check in a high responsibility condition would be mediated by IU. Method: Twenty-seven children and adolescents diagnosed with OCD completed an experimental cognitive appraisal task (CAT) in which they heard two standardised vignettes presented in counterbalanced order; one in which participants were responsible and one in which they were not responsible for preventing harm to a friend’s pet cat. Memory confidence, IU and checking urge were assessed after each scenario using Likert scales. Results: The manipulation of perceived responsibility was successful with children and adolescents rating increased responsibility in the high compared with the low responsibility scenario. There were no differences across high and low responsibility conditions, however, in ratings of memory confidence, IU or the urge to check. There were no significant age-related differences; however, there was a trend for adolescents to report higher ratings across all variables. Finally, the relationship between perceived inflated responsibility and the urge to check was not mediated by IU. Conclusions: Responsibility is not related to ratings of memory confidence, IU or the urge to check in a pediatric sample, suggesting that biases of responsibility may not be central to the formulation of childhood OCD. Results are discussed in terms of implications for cognitive formulations and cognitive approaches to treatment in pediatric OCD.